21525288909 has 4 divisors (see below), whose sum is σ = 28700385216. Its totient is φ = 14350192604.

The previous prime is 21525288901. The next prime is 21525288943. The reversal of 21525288909 is 90988252512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21525288909 - 2³ = 21525288901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525288901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3587548149 + ... + 3587548154.

It is an arithmetic number, because the mean of its divisors is an integer number (7175096304).

Almost surely, 2^21525288909 is an apocalyptic number.

It is an amenable number.

21525288909 is a deficient number, since it is larger than the sum of its proper divisors (7175096307).

21525288909 is an equidigital number, since it uses as much as digits as its factorization.

21525288909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7175096306.

The product of its (nonzero) digits is 1036800, while the sum is 51.

The spelling of 21525288909 in words is "twenty-one billion, five hundred twenty-five million, two hundred eighty-eight thousand, nine hundred nine".