31311661 has 2 divisors, whose sum is σ = 31311662. Its totient is φ = 31311660.

The previous prime is 31311649. The next prime is 31311689. The reversal of 31311661 is 16611313.

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., 25694761 + 5616900 = 5069^2 + 2370^2 .

It is a cyclic number.

It is not a de Polignac number, because 31311661 - 2¹⁵ = 31278893 is a prime.

It is a super-2 number, since 2×31311661² = 1960840229157842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31311461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15655830 + 15655831.

It is an arithmetic number, because the mean of its divisors is an integer number (15655831).

Almost surely, 2^31311661 is an apocalyptic number.

It is an amenable number.

31311661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31311661 is an equidigital number, since it uses as much as digits as its factorization.

31311661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 324, while the sum is 22.

The square root of 31311661 is about 5595.6823533864. The cubic root of 31311661 is about 315.1872943432.

Adding to 31311661 its reverse (16611313), we get a palindrome (47922974).

The spelling of 31311661 in words is "thirty-one million, three hundred eleven thousand, six hundred sixty-one".