21799500021 has 12 divisors (see below), whose sum is σ = 33910333548. Its totient is φ = 13415076864.

The previous prime is 21799499989. The next prime is 21799500053. The reversal of 21799500021 is 12000599712.

It is an interprime number because it is at equal distance from previous prime (21799499989) and next prime (21799500053).

It can be written as a sum of positive squares in 2 ways, for example, as 1582925796 + 20216574225 = 39786^2 + 142185^2 .

It is not a de Polignac number, because 21799500021 - 2⁵ = 21799499989 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21799100021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 93160140 + ... + 93160373.

It is an arithmetic number, because the mean of its divisors is an integer number (2825861129).

Almost surely, 2^21799500021 is an apocalyptic number.

It is an amenable number.

21799500021 is a deficient number, since it is larger than the sum of its proper divisors (12110833527).

21799500021 is a wasteful number, since it uses less digits than its factorization.

21799500021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186320532 (or 186320529 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 36.

The spelling of 21799500021 in words is "twenty-one billion, seven hundred ninety-nine million, five hundred thousand, twenty-one".