660091961 has 2 divisors, whose sum is σ = 660091962. Its totient is φ = 660091960.

The previous prime is 660091937. The next prime is 660091987. The reversal of 660091961 is 169190066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602407936 + 57684025 = 24544^2 + 7595^2 .

It is a cyclic number.

It is not a de Polignac number, because 660091961 - 2¹⁸ = 659829817 is a prime.

It is not a weakly prime, because it can be changed into another prime (660091931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330045980 + 330045981.

It is an arithmetic number, because the mean of its divisors is an integer number (330045981).

Almost surely, 2^660091961 is an apocalyptic number.

It is an amenable number.

660091961 is a deficient number, since it is larger than the sum of its proper divisors (1).

660091961 is an equidigital number, since it uses as much as digits as its factorization.

660091961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 660091961 is about 25692.2548835247. The cubic root of 660091961 is about 870.6992049419.

The spelling of 660091961 in words is "six hundred sixty million, ninety-one thousand, nine hundred sixty-one".