21313012021 has 24 divisors (see below), whose sum is σ = 25901718840. Its totient is φ = 17463600000.

The previous prime is 21313011997. The next prime is 21313012043. The reversal of 21313012021 is 12021031312.

It can be written as a sum of positive squares in 4 ways, for example, as 5784363025 + 15528648996 = 76055^2 + 124614^2 .

It is not a de Polignac number, because 21313012021 - 2¹⁷ = 21312880949 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21313011986 and 21313012004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21313012051) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 69271 + ... + 217771.

It is an arithmetic number, because the mean of its divisors is an integer number (1079238285).

Almost surely, 2^21313012021 is an apocalyptic number.

It is an amenable number.

21313012021 is a deficient number, since it is larger than the sum of its proper divisors (4588706819).

21313012021 is a wasteful number, since it uses less digits than its factorization.

21313012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148645 (or 148638 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21313012021 its reverse (12021031312), we get a palindrome (33334043333).

The spelling of 21313012021 in words is "twenty-one billion, three hundred thirteen million, twelve thousand, twenty-one".