31621661 has 2 divisors, whose sum is σ = 31621662. Its totient is φ = 31621660.

The previous prime is 31621651. The next prime is 31621669. The reversal of 31621661 is 16612613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26977636 + 4644025 = 5194^2 + 2155^2 .

It is an emirp because it is prime and its reverse (16612613) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31621661 - 2²² = 27427357 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31621661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31621669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15810830 + 15810831.

It is an arithmetic number, because the mean of its divisors is an integer number (15810831).

Almost surely, 2^31621661 is an apocalyptic number.

It is an amenable number.

31621661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31621661 is an equidigital number, since it uses as much as digits as its factorization.

31621661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 26.

The square root of 31621661 is about 5623.3140584534. The cubic root of 31621661 is about 316.2240473008.

The spelling of 31621661 in words is "thirty-one million, six hundred twenty-one thousand, six hundred sixty-one".