21507463656436 has 6 divisors (see below), whose sum is σ = 37638061398770. Its totient is φ = 10753731828216.

The previous prime is 21507463656379. The next prime is 21507463656443. The reversal of 21507463656436 is 63465636470512.

It can be written as a sum of positive squares in only one way, i.e., 21171446347536 + 336017308900 = 4601244^2 + 579670^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2688432957051 + ... + 2688432957058.

Almost surely, 2^{21507463656436} is an apocalyptic number.

It is an amenable number.

21507463656436 is a deficient number, since it is larger than the sum of its proper divisors (16130597742334).

21507463656436 is a wasteful number, since it uses less digits than its factorization.

21507463656436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5376865914113 (or 5376865914111 counting only the distinct ones).

The product of its (nonzero) digits is 65318400, while the sum is 58.

The spelling of 21507463656436 in words is "twenty-one trillion, five hundred seven billion, four hundred sixty-three million, six hundred fifty-six thousand, four hundred thirty-six".