21255440313 has 4 divisors (see below), whose sum is σ = 28340587088. Its totient is φ = 14170293540.

The previous prime is 21255440303. The next prime is 21255440387. The reversal of 21255440313 is 31304455212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21255440313 - 2¹⁷ = 21255309241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255440303) 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, 3542573383 + ... + 3542573388.

It is an arithmetic number, because the mean of its divisors is an integer number (7085146772).

Almost surely, 2^21255440313 is an apocalyptic number.

It is an amenable number.

21255440313 is a deficient number, since it is larger than the sum of its proper divisors (7085146775).

21255440313 is an equidigital number, since it uses as much as digits as its factorization.

21255440313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7085146774.

The product of its (nonzero) digits is 14400, while the sum is 30.

Adding to 21255440313 its reverse (31304455212), we get a palindrome (52559895525).

The spelling of 21255440313 in words is "twenty-one billion, two hundred fifty-five million, four hundred forty thousand, three hundred thirteen".