21506703148656 has 180 divisors, whose sum is σ = 66305414775600. Its totient is φ = 6502665523200.

The previous prime is 21506703148639. The next prime is 21506703148771. The reversal of 21506703148656 is 65684130760512.

It is a happy number.

21506703148656 is a `hidden beast` number, since 2 + 1 + 50 + 67 + 0 + 3 + 1 + 486 + 56 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 6448861 + ... + 9197891.

It is an arithmetic number, because the mean of its divisors is an integer number (368363415420).

Almost surely, 2^{21506703148656} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21506703148656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33152707387800).

21506703148656 is an abundant number, since it is smaller than the sum of its proper divisors (44798711626944).

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

21506703148656 is a wasteful number, since it uses less digits than its factorization.

21506703148656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2749516 (or 2749496 counting only the distinct ones).

The product of its (nonzero) digits is 7257600, while the sum is 54.

The spelling of 21506703148656 in words is "twenty-one trillion, five hundred six billion, seven hundred three million, one hundred forty-eight thousand, six hundred fifty-six".