640417858 has 4 divisors (see below), whose sum is σ = 960626790. Its totient is φ = 320208928.

The previous prime is 640417853. The next prime is 640417859. The reversal of 640417858 is 858714046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 858714046 = 2 ⋅429357023.

It can be written as a sum of positive squares in only one way, i.e., 638421289 + 1996569 = 25267^2 + 1413^2 .

It is not an unprimeable number, because it can be changed into a prime (640417853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160104463 + ... + 160104466.

Almost surely, 2^640417858 is an apocalyptic number.

640417858 is a deficient number, since it is larger than the sum of its proper divisors (320208932).

640417858 is a wasteful number, since it uses less digits than its factorization.

640417858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320208931.

The product of its (nonzero) digits is 215040, while the sum is 43.

The square root of 640417858 is about 25306.4785776291. The cubic root of 640417858 is about 861.9613868288.

The spelling of 640417858 in words is "six hundred forty million, four hundred seventeen thousand, eight hundred fifty-eight".