21368293257 has 4 divisors (see below), whose sum is σ = 28491057680. Its totient is φ = 14245528836.

The previous prime is 21368293253. The next prime is 21368293291. The reversal of 21368293257 is 75239286312.

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 21368293257 - 2² = 21368293253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21368293253) 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, 3561382207 + ... + 3561382212.

It is an arithmetic number, because the mean of its divisors is an integer number (7122764420).

Almost surely, 2^21368293257 is an apocalyptic number.

It is an amenable number.

21368293257 is a deficient number, since it is larger than the sum of its proper divisors (7122764423).

21368293257 is an equidigital number, since it uses as much as digits as its factorization.

21368293257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7122764422.

The product of its digits is 1088640, while the sum is 48.

The spelling of 21368293257 in words is "twenty-one billion, three hundred sixty-eight million, two hundred ninety-three thousand, two hundred fifty-seven".