21704991165 has 96 divisors (see below), whose sum is σ = 44472564864. Its totient is φ = 9654059520.

The previous prime is 21704991163. The next prime is 21704991193. The reversal of 21704991165 is 56119940712.

21704991165 is a `hidden beast` number, since 21 + 70 + 499 + 11 + 65 = 666.

It is not a de Polignac number, because 21704991165 - 2¹ = 21704991163 is a prime.

It is a super-2 number, since 2×21704991165² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21704991165.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21704991163) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1038559 + ... + 1059251.

It is an arithmetic number, because the mean of its divisors is an integer number (463255884).

Almost surely, 2^21704991165 is an apocalyptic number.

It is an amenable number.

21704991165 is an abundant number, since it is smaller than the sum of its proper divisors (22767573699).

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

21704991165 is a wasteful number, since it uses less digits than its factorization.

21704991165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20891 (or 20888 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The spelling of 21704991165 in words is "twenty-one billion, seven hundred four million, nine hundred ninety-one thousand, one hundred sixty-five".