21012031231 has 8 divisors (see below), whose sum is σ = 21041853984. Its totient is φ = 20982232320.

The previous prime is 21012031211. The next prime is 21012031237. The reversal of 21012031231 is 13213021012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21012031231 - 2²³ = 21003642623 is a prime.

It is a super-2 number, since 2×21012031231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012031237) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2381430 + ... + 2390236.

It is an arithmetic number, because the mean of its divisors is an integer number (2630231748).

Almost surely, 2^21012031231 is an apocalyptic number.

21012031231 is a deficient number, since it is larger than the sum of its proper divisors (29822753).

21012031231 is a wasteful number, since it uses less digits than its factorization.

21012031231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11921.

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

Adding to 21012031231 its reverse (13213021012), we get a palindrome (34225052243).

The spelling of 21012031231 in words is "twenty-one billion, twelve million, thirty-one thousand, two hundred thirty-one".