21123131534 has 16 divisors (see below), whose sum is σ = 32782227120. Its totient is φ = 10195832640.

The previous prime is 21123131527. The next prime is 21123131551. The reversal of 21123131534 is 43513132112.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 422402 + ... + 469754.

It is an arithmetic number, because the mean of its divisors is an integer number (2048889195).

Almost surely, 2^21123131534 is an apocalyptic number.

21123131534 is a deficient number, since it is larger than the sum of its proper divisors (11659095586).

21123131534 is a wasteful number, since it uses less digits than its factorization.

21123131534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55075.

The product of its digits is 2160, while the sum is 26.

Adding to 21123131534 its reverse (43513132112), we get a palindrome (64636263646).

The spelling of 21123131534 in words is "twenty-one billion, one hundred twenty-three million, one hundred thirty-one thousand, five hundred thirty-four".