664173761 has 2 divisors, whose sum is σ = 664173762. Its totient is φ = 664173760.

The previous prime is 664173749. The next prime is 664173787. The reversal of 664173761 is 167371466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602457025 + 61716736 = 24545^2 + 7856^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664173761 is a prime.

It is a super-2 number, since 2×664173761² = 882253569601770242, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (664173721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332086880 + 332086881.

It is an arithmetic number, because the mean of its divisors is an integer number (332086881).

Almost surely, 2^664173761 is an apocalyptic number.

It is an amenable number.

664173761 is a deficient number, since it is larger than the sum of its proper divisors (1).

664173761 is an equidigital number, since it uses as much as digits as its factorization.

664173761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 41.

The square root of 664173761 is about 25771.5688501884. The cubic root of 664173761 is about 872.4902278307.

The spelling of 664173761 in words is "six hundred sixty-four million, one hundred seventy-three thousand, seven hundred sixty-one".