21807860261 has 16 divisors (see below), whose sum is σ = 25092426240. Its totient is φ = 18744459120.

The previous prime is 21807860257. The next prime is 21807860267. The reversal of 21807860261 is 16206870812.

It is not a de Polignac number, because 21807860261 - 2² = 21807860257 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 (21807860267) 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, 1406 + ... + 208848.

It is an arithmetic number, because the mean of its divisors is an integer number (1568276640).

Almost surely, 2^21807860261 is an apocalyptic number.

It is an amenable number.

21807860261 is a deficient number, since it is larger than the sum of its proper divisors (3284565979).

21807860261 is a wasteful number, since it uses less digits than its factorization.

21807860261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207976.

The product of its (nonzero) digits is 64512, while the sum is 41.

The spelling of 21807860261 in words is "twenty-one billion, eight hundred seven million, eight hundred sixty thousand, two hundred sixty-one".