31913925661 has 2 divisors, whose sum is σ = 31913925662. Its totient is φ = 31913925660.

The previous prime is 31913925607. The next prime is 31913925677. The reversal of 31913925661 is 16652931913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30363062500 + 1550863161 = 174250^2 + 39381^2 .

It is an emirp because it is prime and its reverse (16652931913) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31913925661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31913925691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15956962830 + 15956962831.

It is an arithmetic number, because the mean of its divisors is an integer number (15956962831).

Almost surely, 2^31913925661 is an apocalyptic number.

It is an amenable number.

31913925661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31913925661 is an equidigital number, since it uses as much as digits as its factorization.

31913925661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 262440, while the sum is 46.

The spelling of 31913925661 in words is "thirty-one billion, nine hundred thirteen million, nine hundred twenty-five thousand, six hundred sixty-one".