21105657500 has 30 divisors (see below), whose sum is σ = 46153857288. Its totient is φ = 8442262000.

The previous prime is 21105657499. The next prime is 21105657523. The reversal of 21105657500 is 575650112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4218632 + ... + 4223631.

Almost surely, 2^21105657500 is an apocalyptic number.

21105657500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105657500 is an abundant number, since it is smaller than the sum of its proper divisors (25048199788).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21105657500 is an equidigital number, since it uses as much as digits as its factorization.

21105657500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8442287 (or 8442270 counting only the distinct ones).

The product of its (nonzero) digits is 10500, while the sum is 32.

The spelling of 21105657500 in words is "twenty-one billion, one hundred five million, six hundred fifty-seven thousand, five hundred".