21860210021 has 16 divisors (see below), whose sum is σ = 23694198528. Its totient is φ = 20048212800.

The previous prime is 21860209967. The next prime is 21860210051. The reversal of 21860210021 is 12001206812.

It is a cyclic number.

It is not a de Polignac number, because 21860210021 - 2²⁶ = 21793101157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21860210051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2892770 + ... + 2900316.

It is an arithmetic number, because the mean of its divisors is an integer number (1480887408).

Almost surely, 2^21860210021 is an apocalyptic number.

It is an amenable number.

21860210021 is a deficient number, since it is larger than the sum of its proper divisors (1833988507).

21860210021 is a wasteful number, since it uses less digits than its factorization.

21860210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8972.

The product of its (nonzero) digits is 384, while the sum is 23.

Adding to 21860210021 its reverse (12001206812), we get a palindrome (33861416833).

The spelling of 21860210021 in words is "twenty-one billion, eight hundred sixty million, two hundred ten thousand, twenty-one".