21506633390517 has 32 divisors (see below), whose sum is σ = 32665039534080. Its totient is φ = 12458996742720.

The previous prime is 21506633390497. The next prime is 21506633390639. The reversal of 21506633390517 is 71509333660512.

It is not a de Polignac number, because 21506633390517 - 2⁸ = 21506633390261 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21506633390517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506633390717) 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, 8692842 + ... + 10889387.

It is an arithmetic number, because the mean of its divisors is an integer number (1020782485440).

Almost surely, 2^{21506633390517} is an apocalyptic number.

It is an amenable number.

21506633390517 is a deficient number, since it is larger than the sum of its proper divisors (11158406143563).

21506633390517 is a wasteful number, since it uses less digits than its factorization.

21506633390517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19583713.

The product of its (nonzero) digits is 3061800, while the sum is 51.

The spelling of 21506633390517 in words is "twenty-one trillion, five hundred six billion, six hundred thirty-three million, three hundred ninety thousand, five hundred seventeen".