21017636914721 has 16 divisors (see below), whose sum is σ = 21539182742784. Its totient is φ = 20499196725504.

The previous prime is 21017636914649. The next prime is 21017636914759. The reversal of 21017636914721 is 12741963671012.

It is a cyclic number.

It is not a de Polignac number, because 21017636914721 - 2²⁶ = 21017569805857 is a prime.

It is a super-2 number, since 2×21017636914721² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21017636914721.

It is not an unprimeable number, because it can be changed into a prime (21017636914321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 519793721 + ... + 519834153.

It is an arithmetic number, because the mean of its divisors is an integer number (1346198921424).

Almost surely, 2^{21017636914721} is an apocalyptic number.

It is an amenable number.

21017636914721 is a deficient number, since it is larger than the sum of its proper divisors (521545828063).

21017636914721 is a wasteful number, since it uses less digits than its factorization.

21017636914721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78520.

The product of its (nonzero) digits is 762048, while the sum is 50.

The spelling of 21017636914721 in words is "twenty-one trillion, seventeen billion, six hundred thirty-six million, nine hundred fourteen thousand, seven hundred twenty-one".