21121020231 has 16 divisors (see below), whose sum is σ = 28826497920. Its totient is φ = 13748343840.

The previous prime is 21121020229. The next prime is 21121020233. The reversal of 21121020231 is 13202012112.

It is an interprime number because it is at equal distance from previous prime (21121020229) and next prime (21121020233).

It is not a de Polignac number, because 21121020231 - 2¹ = 21121020229 is a prime.

It is a super-2 number, since 2×21121020231² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121020231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121020233) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 355705 + ... + 410813.

It is an arithmetic number, because the mean of its divisors is an integer number (1801656120).

Almost surely, 2^21121020231 is an apocalyptic number.

21121020231 is a deficient number, since it is larger than the sum of its proper divisors (7705477689).

21121020231 is a wasteful number, since it uses less digits than its factorization.

21121020231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58126.

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21121020231 its reverse (13202012112), we get a palindrome (34323032343).

The spelling of 21121020231 in words is "twenty-one billion, one hundred twenty-one million, twenty thousand, two hundred thirty-one".