21865699051 has 4 divisors (see below), whose sum is σ = 24989370352. Its totient is φ = 18742027752.

The previous prime is 21865699049. The next prime is 21865699057. The reversal of 21865699051 is 15099656812.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21865699051 - 2¹ = 21865699049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21865699051.

It is not an unprimeable number, because it can be changed into a prime (21865699057) 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, 1561835640 + ... + 1561835653.

It is an arithmetic number, because the mean of its divisors is an integer number (6247342588).

Almost surely, 2^21865699051 is an apocalyptic number.

21865699051 is a deficient number, since it is larger than the sum of its proper divisors (3123671301).

21865699051 is an equidigital number, since it uses as much as digits as its factorization.

21865699051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3123671300.

The product of its (nonzero) digits is 1166400, while the sum is 52.

The spelling of 21865699051 in words is "twenty-one billion, eight hundred sixty-five million, six hundred ninety-nine thousand, fifty-one".