31012213021 has 2 divisors, whose sum is σ = 31012213022. Its totient is φ = 31012213020.

The previous prime is 31012213013. The next prime is 31012213033. The reversal of 31012213021 is 12031221013.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30135224025 + 876988996 = 173595^2 + 29614^2 .

It is a cyclic number.

It is not a de Polignac number, because 31012213021 - 2³ = 31012213013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31012212986 and 31012213004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31012213321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15506106510 + 15506106511.

It is an arithmetic number, because the mean of its divisors is an integer number (15506106511).

Almost surely, 2^31012213021 is an apocalyptic number.

It is an amenable number.

31012213021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31012213021 is an equidigital number, since it uses as much as digits as its factorization.

31012213021 is an evil number, because the sum of its binary digits is even.

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

Adding to 31012213021 its reverse (12031221013), we get a palindrome (43043434034).

It can be divided in two parts, 3101 and 2213021, that added together give a palindrome (2216122).

The spelling of 31012213021 in words is "thirty-one billion, twelve million, two hundred thirteen thousand, twenty-one".