21709863424656 has 160 divisors (see below), whose sum is σ = 69638439104640. Its totient is φ = 6418289203200.

The previous prime is 21709863424603. The next prime is 21709863424657. The reversal of 21709863424656 is 65642436890712.

21709863424656 is a `hidden beast` number, since 2 + 1 + 7 + 0 + 98 + 63 + 424 + 65 + 6 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21709863424593 and 21709863424602.

It is not an unprimeable number, because it can be changed into a prime (21709863424657) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 55519485 + ... + 55909148.

It is an arithmetic number, because the mean of its divisors is an integer number (435240244404).

It is a 1-persistent number, because it is pandigital, but 2⋅21709863424656 = 43419726849312 is not.

Almost surely, 2^{21709863424656} is an apocalyptic number.

It is an amenable number.

21709863424656 is an abundant number, since it is smaller than the sum of its proper divisors (47928575679984).

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

21709863424656 is a wasteful number, since it uses less digits than its factorization.

21709863424656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111428702 (or 111428690 counting only the distinct ones).

The product of its (nonzero) digits is 104509440, while the sum is 63.

The spelling of 21709863424656 in words is "twenty-one trillion, seven hundred nine billion, eight hundred sixty-three million, four hundred twenty-four thousand, six hundred fifty-six".