31540211561 has 2 divisors, whose sum is σ = 31540211562. Its totient is φ = 31540211560.

The previous prime is 31540211539. The next prime is 31540211569. The reversal of 31540211561 is 16511204513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17887457536 + 13652754025 = 133744^2 + 116845^2 .

It is a cyclic number.

It is not a de Polignac number, because 31540211561 - 2¹⁴ = 31540195177 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31540211569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15770105780 + 15770105781.

It is an arithmetic number, because the mean of its divisors is an integer number (15770105781).

Almost surely, 2^31540211561 is an apocalyptic number.

It is an amenable number.

31540211561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31540211561 is an equidigital number, since it uses as much as digits as its factorization.

31540211561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 29.

The spelling of 31540211561 in words is "thirty-one billion, five hundred forty million, two hundred eleven thousand, five hundred sixty-one".