21525857901 has 6 divisors (see below), whose sum is σ = 31092905870. Its totient is φ = 14350571928.

The previous prime is 21525857867. The next prime is 21525857909. The reversal of 21525857901 is 10975852512.

21525857901 is a `hidden beast` number, since 21 + 5 + 2 + 58 + 579 + 0 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12176901801 + 9348956100 = 110349^2 + 96690^2 .

It is not a de Polignac number, because 21525857901 - 2²⁹ = 20988986989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525857909) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1195880986 + ... + 1195881003.

Almost surely, 2^21525857901 is an apocalyptic number.

It is an amenable number.

21525857901 is a deficient number, since it is larger than the sum of its proper divisors (9567047969).

21525857901 is a wasteful number, since it uses less digits than its factorization.

21525857901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2391761995 (or 2391761992 counting only the distinct ones).

The product of its (nonzero) digits is 252000, while the sum is 45.

The spelling of 21525857901 in words is "twenty-one billion, five hundred twenty-five million, eight hundred fifty-seven thousand, nine hundred one".