21025865221 has 8 divisors (see below), whose sum is σ = 21547951488. Its totient is φ = 20504220000.

The previous prime is 21025865197. The next prime is 21025865269. The reversal of 21025865221 is 12256852012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21025865221 - 2⁹ = 21025864709 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 (21025865281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12675 + ... + 205456.

It is an arithmetic number, because the mean of its divisors is an integer number (2693493936).

Almost surely, 2^21025865221 is an apocalyptic number.

It is an amenable number.

21025865221 is a deficient number, since it is larger than the sum of its proper divisors (522086267).

21025865221 is a wasteful number, since it uses less digits than its factorization.

21025865221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220523.

The product of its (nonzero) digits is 19200, while the sum is 34.

The spelling of 21025865221 in words is "twenty-one billion, twenty-five million, eight hundred sixty-five thousand, two hundred twenty-one".