21855583765 has 16 divisors (see below), whose sum is σ = 26727636096. Its totient is φ = 17150660800.

The previous prime is 21855583759. The next prime is 21855583769. The reversal of 21855583765 is 56738555812.

It is not a de Polignac number, because 21855583765 - 2²³ = 21847195157 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 (21855583769) 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, 1841400 + ... + 1853230.

It is an arithmetic number, because the mean of its divisors is an integer number (1670477256).

Almost surely, 2^21855583765 is an apocalyptic number.

It is an amenable number.

21855583765 is a deficient number, since it is larger than the sum of its proper divisors (4872052331).

21855583765 is a wasteful number, since it uses less digits than its factorization.

21855583765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18860.

The product of its digits is 10080000, while the sum is 55.

The spelling of 21855583765 in words is "twenty-one billion, eight hundred fifty-five million, five hundred eighty-three thousand, seven hundred sixty-five".