21120394510656 has 224 divisors, whose sum is σ = 71588025358080. Its totient is φ = 5980996288512.

The previous prime is 21120394510643. The next prime is 21120394510711. The reversal of 21120394510656 is 65601549302112.

It is a happy number.

21120394510656 is a `hidden beast` number, since 2 + 1 + 120 + 3 + 9 + 4 + 510 + 6 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6359101 + ... + 9092796.

It is an arithmetic number, because the mean of its divisors is an integer number (319589398920).

Almost surely, 2^{21120394510656} is an apocalyptic number.

It is an amenable number.

21120394510656 is an abundant number, since it is smaller than the sum of its proper divisors (50467630847424).

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

21120394510656 is a wasteful number, since it uses less digits than its factorization.

21120394510656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15452038 (or 15452022 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The spelling of 21120394510656 in words is "twenty-one trillion, one hundred twenty billion, three hundred ninety-four million, five hundred ten thousand, six hundred fifty-six".