21312253511 has 4 divisors (see below), whose sum is σ = 21523266024. Its totient is φ = 21101241000.

The previous prime is 21312253493. The next prime is 21312253531. The reversal of 21312253511 is 11535221312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21312253511 - 2²² = 21308059207 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 (21312253531) 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, 105506105 + ... + 105506306.

It is an arithmetic number, because the mean of its divisors is an integer number (5380816506).

Almost surely, 2^21312253511 is an apocalyptic number.

21312253511 is a deficient number, since it is larger than the sum of its proper divisors (211012513).

21312253511 is a wasteful number, since it uses less digits than its factorization.

21312253511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211012512.

The product of its digits is 1800, while the sum is 26.

Adding to 21312253511 its reverse (11535221312), we get a palindrome (32847474823).

The spelling of 21312253511 in words is "twenty-one billion, three hundred twelve million, two hundred fifty-three thousand, five hundred eleven".