21634573221 has 12 divisors (see below), whose sum is σ = 31257694572. Its totient is φ = 14419469376.

The previous prime is 21634573183. The next prime is 21634573223. The reversal of 21634573221 is 12237543612.

21634573221 is a `hidden beast` number, since 2 + 1 + 63 + 4 + 573 + 2 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 17866332225 + 3768240996 = 133665^2 + 61386^2 .

It is not a de Polignac number, because 21634573221 - 2¹⁷ = 21634442149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21634573223) 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, 259746 + ... + 332771.

It is an arithmetic number, because the mean of its divisors is an integer number (2604807881).

Almost surely, 2^21634573221 is an apocalyptic number.

It is an amenable number.

21634573221 is a deficient number, since it is larger than the sum of its proper divisors (9623121351).

21634573221 is a wasteful number, since it uses less digits than its factorization.

21634573221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 596580 (or 596577 counting only the distinct ones).

The product of its digits is 60480, while the sum is 36.

The spelling of 21634573221 in words is "twenty-one billion, six hundred thirty-four million, five hundred seventy-three thousand, two hundred twenty-one".