21311020255 has 32 divisors (see below), whose sum is σ = 30778675200. Its totient is φ = 13837900032.

The previous prime is 21311020253. The next prime is 21311020309. The reversal of 21311020255 is 55202011312.

It is not a de Polignac number, because 21311020255 - 2¹ = 21311020253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311020253) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1808914 + ... + 1820656.

It is an arithmetic number, because the mean of its divisors is an integer number (961833600).

Almost surely, 2^21311020255 is an apocalyptic number.

21311020255 is a deficient number, since it is larger than the sum of its proper divisors (9467654945).

21311020255 is a wasteful number, since it uses less digits than its factorization.

21311020255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14503.

The product of its (nonzero) digits is 600, while the sum is 22.

Adding to 21311020255 its reverse (55202011312), we get a palindrome (76513031567).

The spelling of 21311020255 in words is "twenty-one billion, three hundred eleven million, twenty thousand, two hundred fifty-five".