640318898 has 18 divisors (see below), whose sum is σ = 996355191. Its totient is φ = 308618464.

The previous prime is 640318897. The next prime is 640318909. The reversal of 640318898 is 898813046.

It can be written as a sum of positive squares in 5 ways, for example, as 24137569 + 616181329 = 4913^2 + 24823^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=17893.

It is a super-2 number, since 2×640318898² = 820016582271868808, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640318897) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1037486 + ... + 1038102.

Almost surely, 2^640318898 is an apocalyptic number.

640318898 is a deficient number, since it is larger than the sum of its proper divisors (356036293).

640318898 is an frugal number, since it uses more digits than its factorization.

640318898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1294 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 47.

The square root of 640318898 is about 25304.5232715418. The cubic root of 640318898 is about 861.9169866028.

The spelling of 640318898 in words is "six hundred forty million, three hundred eighteen thousand, eight hundred ninety-eight".