31643111561 has 2 divisors, whose sum is σ = 31643111562. Its totient is φ = 31643111560.

The previous prime is 31643111501. The next prime is 31643111567. The reversal of 31643111561 is 16511134613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31495245961 + 147865600 = 177469^2 + 12160^2 .

It is an emirp because it is prime and its reverse (16511134613) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31643111561 is a prime.

It is not a weakly prime, because it can be changed into another prime (31643111567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15821555780 + 15821555781.

It is an arithmetic number, because the mean of its divisors is an integer number (15821555781).

Almost surely, 2^31643111561 is an apocalyptic number.

It is an amenable number.

31643111561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31643111561 is an equidigital number, since it uses as much as digits as its factorization.

31643111561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 32.

The spelling of 31643111561 in words is "thirty-one billion, six hundred forty-three million, one hundred eleven thousand, five hundred sixty-one".