21002020031 has 16 divisors (see below), whose sum is σ = 23395508640. Its totient is φ = 18763269120.

The previous prime is 21002019959. The next prime is 21002020043. The reversal of 21002020031 is 13002020012.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002020031 is a prime.

It is a super-2 number, since 2×21002020031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002019994 and 21002020021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002020051) 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, 381401 + ... + 432978.

It is an arithmetic number, because the mean of its divisors is an integer number (1462219290).

Almost surely, 2^21002020031 is an apocalyptic number.

21002020031 is a deficient number, since it is larger than the sum of its proper divisors (2393488609).

21002020031 is a wasteful number, since it uses less digits than its factorization.

21002020031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814474.

The product of its (nonzero) digits is 24, while the sum is 11.

Adding to 21002020031 its reverse (13002020012), we get a palindrome (34004040043).

The spelling of 21002020031 in words is "twenty-one billion, two million, twenty thousand, thirty-one".