64640669 has 2 divisors, whose sum is σ = 64640670. Its totient is φ = 64640668.

The previous prime is 64640627. The next prime is 64640671. The reversal of 64640669 is 96604646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43388569 + 21252100 = 6587^2 + 4610^2 .

It is a cyclic number.

It is not a de Polignac number, because 64640669 - 2¹² = 64636573 is a prime.

It is a super-2 number, since 2×64640669² = 8356832177535122, which contains 22 as substring.

Together with 64640671, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64640269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32320334 + 32320335.

It is an arithmetic number, because the mean of its divisors is an integer number (32320335).

Almost surely, 2^64640669 is an apocalyptic number.

It is an amenable number.

64640669 is a deficient number, since it is larger than the sum of its proper divisors (1).

64640669 is an equidigital number, since it uses as much as digits as its factorization.

64640669 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 186624, while the sum is 41.

The square root of 64640669 is about 8039.9421017816. The cubic root of 64640669 is about 401.3302979471.

The spelling of 64640669 in words is "sixty-four million, six hundred forty thousand, six hundred sixty-nine".