• Go

s := strconv.FormatInt(int64(n), b)

• JS

let s = n.toString(b);

• Java

String s = Integer.toString(n, b);

• Pascal

function IntToBaseStr(n: longword; const b: cardinal): string;
const
  digits = '0123456789abcdefghijklmnopqrstuvwxyz';
var
  remainder: longword;
begin
  Result := '';
  repeat
    DivMod(n, b, n, remainder);
    result := digits[remainder + 1] + result;
  until n = 0;
end;

• Pascal

s := IntToStrBase(n,b);

• Perl

sub int_to_base_str {
    my ($n, $b) = @_;
    my $digits = '0123456789abcdefghijklmnopqrstuvwxyz';
    my ($s, $q, $remainder) = ('');

    return '0' if $n == 0;

    use integer;

    while ($n) {
        ($n, $remainder) = ($n / $b, $n % $b), 
        $s = substr($digits, $remainder, 1) . $s;
    }

    return $s
}

• Python

def int_to_base_str(n, b):
    digits = '0123456789abcdefghijklmnopqrstuvwxyz'
    s = ''
    if n == 0: return '0'
    while n:
        n, remainder = divmod(n, b)
        s = digits[remainder] + s
    return s

• Python

s = numpy.base_repr(n, b)

• Python

a, s = digits + ascii_letters, ''
while n:
    s = a[n % b] + s
    n = n // b

• Python

a, s = printable.rstrip(), ''
while n:
    s = a[n % b] + s
    n = n // b

• Ruby

s = n.to_s(b)

• Rust

let s = radix(n, b);