21257381279 has 16 divisors (see below), whose sum is σ = 22555327200. Its totient is φ = 19977560064.

The previous prime is 21257381273. The next prime is 21257381291. The reversal of 21257381279 is 97218375212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21257381279 - 2²⁰ = 21256332703 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 (21257381273) 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, 6997949 + ... + 7000985.

It is an arithmetic number, because the mean of its divisors is an integer number (1409707950).

Almost surely, 2^21257381279 is an apocalyptic number.

21257381279 is a deficient number, since it is larger than the sum of its proper divisors (1297945921).

21257381279 is a wasteful number, since it uses less digits than its factorization.

21257381279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5882.

The product of its digits is 423360, while the sum is 47.

The spelling of 21257381279 in words is "twenty-one billion, two hundred fifty-seven million, three hundred eighty-one thousand, two hundred seventy-nine".