21431312021 has 24 divisors (see below), whose sum is σ = 26063209536. Its totient is φ = 17259379200.

The previous prime is 21431311997. The next prime is 21431312033. The reversal of 21431312021 is 12021313412.

It is not a de Polignac number, because 21431312021 - 2¹⁰ = 21431310997 is a prime.

It is a super-2 number, since 2×21431312021² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21431311984 and 21431312002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431312081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1207010 + ... + 1224636.

It is an arithmetic number, because the mean of its divisors is an integer number (1085967064).

Almost surely, 2^21431312021 is an apocalyptic number.

It is an amenable number.

21431312021 is a deficient number, since it is larger than the sum of its proper divisors (4631897515).

21431312021 is a wasteful number, since it uses less digits than its factorization.

21431312021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18269 (or 18252 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 21431312021 its reverse (12021313412), we get a palindrome (33452625433).

The spelling of 21431312021 in words is "twenty-one billion, four hundred thirty-one million, three hundred twelve thousand, twenty-one".