31200020021 has 2 divisors, whose sum is σ = 31200020022. Its totient is φ = 31200020020.

The previous prime is 31200020017. The next prime is 31200020087. The reversal of 31200020021 is 12002000213.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31182262225 + 17757796 = 176585^2 + 4214^2 .

It is a cyclic number.

It is not a de Polignac number, because 31200020021 - 2² = 31200020017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31200019984 and 31200020011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31200020521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15600010010 + 15600010011.

It is an arithmetic number, because the mean of its divisors is an integer number (15600010011).

Almost surely, 2^31200020021 is an apocalyptic number.

It is an amenable number.

31200020021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31200020021 is an equidigital number, since it uses as much as digits as its factorization.

31200020021 is an odious number, because the sum of its binary digits is odd.

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

Adding to 31200020021 its reverse (12002000213), we get a palindrome (43202020234).

The spelling of 31200020021 in words is "thirty-one billion, two hundred million, twenty thousand, twenty-one".