21052781361 has 10 divisors (see below), whose sum is σ = 31449216722. Its totient is φ = 14035187520.

The previous prime is 21052781327. The next prime is 21052781371. The reversal of 21052781361 is 16318725012.

21052781361 is a `hidden beast` number, since 21 + 0 + 5 + 278 + 1 + 361 = 666.

It can be written as a sum of positive squares in only one way, i.e., 15445766961 + 5607014400 = 124281^2 + 74880^2 .

It is not a de Polignac number, because 21052781361 - 2²¹ = 21050684209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21052781371) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 129955360 + ... + 129955521.

Almost surely, 2^21052781361 is an apocalyptic number.

It is an amenable number.

21052781361 is a deficient number, since it is larger than the sum of its proper divisors (10396435361).

21052781361 is an equidigital number, since it uses as much as digits as its factorization.

21052781361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259910893 (or 259910884 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The spelling of 21052781361 in words is "twenty-one billion, fifty-two million, seven hundred eighty-one thousand, three hundred sixty-one".