21156737643600 has 120 divisors (see below), whose sum is σ = 72985320119712. Its totient is φ = 5207812339200.

The previous prime is 21156737643599. The next prime is 21156737643631. The reversal of 21156737643600 is 634673765112.

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 678084966 + ... + 678116165.

Almost surely, 2^{21156737643600} is an apocalyptic number.

21156737643600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21156737643600 is an abundant number, since it is smaller than the sum of its proper divisors (51828582476112).

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

21156737643600 is a wasteful number, since it uses less digits than its factorization.

21156737643600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1356201165 (or 1356201154 counting only the distinct ones).

The product of its (nonzero) digits is 3810240, while the sum is 51.

The spelling of 21156737643600 in words is "twenty-one trillion, one hundred fifty-six billion, seven hundred thirty-seven million, six hundred forty-three thousand, six hundred".