31661660161 has 4 divisors (see below), whose sum is σ = 31734782212. Its totient is φ = 31588538112.

The previous prime is 31661660153. The next prime is 31661660171. The reversal of 31661660161 is 16106616613.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2062522225 + 29599137936 = 45415^2 + 172044^2 .

It is a cyclic number.

It is not a de Polignac number, because 31661660161 - 2³ = 31661660153 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31661660161.

It is not an unprimeable number, because it can be changed into a prime (31661660171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36560376 + ... + 36561241.

It is an arithmetic number, because the mean of its divisors is an integer number (7933695553).

Almost surely, 2^31661660161 is an apocalyptic number.

It is an amenable number.

31661660161 is a deficient number, since it is larger than the sum of its proper divisors (73122051).

31661660161 is an equidigital number, since it uses as much as digits as its factorization.

31661660161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73122050.

The product of its (nonzero) digits is 23328, while the sum is 37.

The spelling of 31661660161 in words is "thirty-one billion, six hundred sixty-one million, six hundred sixty thousand, one hundred sixty-one".