640662889 has 2 divisors, whose sum is σ = 640662890. Its totient is φ = 640662888.

The previous prime is 640662857. The next prime is 640662923. The reversal of 640662889 is 988266046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 532086489 + 108576400 = 23067^2 + 10420^2 .

It is a cyclic number.

It is not a de Polignac number, because 640662889 - 2⁵ = 640662857 is a prime.

It is not a weakly prime, because it can be changed into another prime (640662839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320331444 + 320331445.

It is an arithmetic number, because the mean of its divisors is an integer number (320331445).

Almost surely, 2^640662889 is an apocalyptic number.

It is an amenable number.

640662889 is a deficient number, since it is larger than the sum of its proper divisors (1).

640662889 is an equidigital number, since it uses as much as digits as its factorization.

640662889 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 995328, while the sum is 49.

The square root of 640662889 is about 25311.3193848128. The cubic root of 640662889 is about 862.0713048179.

The spelling of 640662889 in words is "six hundred forty million, six hundred sixty-two thousand, eight hundred eighty-nine".