21313123437 has 4 divisors (see below), whose sum is σ = 28417497920. Its totient is φ = 14208748956.

The previous prime is 21313123423. The next prime is 21313123457. The reversal of 21313123437 is 73432131312.

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 21313123437 - 2⁴ = 21313123421 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 (21313123457) 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, 3552187237 + ... + 3552187242.

It is an arithmetic number, because the mean of its divisors is an integer number (7104374480).

Almost surely, 2^21313123437 is an apocalyptic number.

It is an amenable number.

21313123437 is a deficient number, since it is larger than the sum of its proper divisors (7104374483).

21313123437 is an equidigital number, since it uses as much as digits as its factorization.

21313123437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7104374482.

The product of its digits is 9072, while the sum is 30.

Adding to 21313123437 its reverse (73432131312), we get a palindrome (94745254749).

The spelling of 21313123437 in words is "twenty-one billion, three hundred thirteen million, one hundred twenty-three thousand, four hundred thirty-seven".