66409957 has 2 divisors, whose sum is σ = 66409958. Its totient is φ = 66409956.

The previous prime is 66409943. The next prime is 66409963. The reversal of 66409957 is 75990466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52504516 + 13905441 = 7246^2 + 3729^2 .

It is a cyclic number.

It is not a de Polignac number, because 66409957 - 2⁷ = 66409829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66409457) 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 as a sum of consecutive naturals, namely, 33204978 + 33204979.

It is an arithmetic number, because the mean of its divisors is an integer number (33204979).

Almost surely, 2^66409957 is an apocalyptic number.

It is an amenable number.

66409957 is a deficient number, since it is larger than the sum of its proper divisors (1).

66409957 is an equidigital number, since it uses as much as digits as its factorization.

66409957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 408240, while the sum is 46.

The square root of 66409957 is about 8149.2304544662. The cubic root of 66409957 is about 404.9590102295.

The spelling of 66409957 in words is "sixty-six million, four hundred nine thousand, nine hundred fifty-seven".