1664581601 has 2 divisors, whose sum is σ = 1664581602. Its totient is φ = 1664581600.

The previous prime is 1664581579. The next prime is 1664581627. The reversal of 1664581601 is 1061854661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 892575376 + 772006225 = 29876^2 + 27785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1664581601 is a prime.

It is not a weakly prime, because it can be changed into another prime (1664581631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832290800 + 832290801.

It is an arithmetic number, because the mean of its divisors is an integer number (832290801).

Almost surely, 2^1664581601 is an apocalyptic number.

It is an amenable number.

1664581601 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664581601 is an equidigital number, since it uses as much as digits as its factorization.

1664581601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 1664581601 is about 40799.2843197035. The cubic root of 1664581601 is about 1185.1364714315.

The spelling of 1664581601 in words is "one billion, six hundred sixty-four million, five hundred eighty-one thousand, six hundred one".