31390621 has 2 divisors, whose sum is σ = 31390622. Its totient is φ = 31390620.

The previous prime is 31390577. The next prime is 31390627. The reversal of 31390621 is 12609313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22752900 + 8637721 = 4770^2 + 2939^2 .

It is a cyclic number.

It is not a de Polignac number, because 31390621 - 2⁷ = 31390493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31390627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15695310 + 15695311.

It is an arithmetic number, because the mean of its divisors is an integer number (15695311).

Almost surely, 2^31390621 is an apocalyptic number.

It is an amenable number.

31390621 is a deficient number, since it is larger than the sum of its proper divisors (1).

31390621 is an equidigital number, since it uses as much as digits as its factorization.

31390621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 31390621 is about 5602.7333507851. The cubic root of 31390621 is about 315.4520125293.

Adding to 31390621 its reverse (12609313), we get a palindrome (43999934).

The spelling of 31390621 in words is "thirty-one million, three hundred ninety thousand, six hundred twenty-one".