31621621 has 2 divisors, whose sum is σ = 31621622. Its totient is φ = 31621620.

The previous prime is 31621613. The next prime is 31621631. The reversal of 31621621 is 12612613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27973521 + 3648100 = 5289^2 + 1910^2 .

It is a cyclic number.

It is not a de Polignac number, because 31621621 - 2³ = 31621613 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31621592 and 31621601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31621631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15810810 + 15810811.

It is an arithmetic number, because the mean of its divisors is an integer number (15810811).

Almost surely, 2^31621621 is an apocalyptic number.

It is an amenable number.

31621621 is a deficient number, since it is larger than the sum of its proper divisors (1).

31621621 is an equidigital number, since it uses as much as digits as its factorization.

31621621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 22.

The square root of 31621621 is about 5623.3105018307. The cubic root of 31621621 is about 316.2239139643.

The spelling of 31621621 in words is "thirty-one million, six hundred twenty-one thousand, six hundred twenty-one".