640859408 has 80 divisors (see below), whose sum is σ = 1454359296. Its totient is φ = 267909120.

The previous prime is 640859383. The next prime is 640859449. The reversal of 640859408 is 804958046.

It is a happy number.

It is a super-2 number, since 2×640859408² = 821401561644220928, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 841748 + ... + 842508.

Almost surely, 2^640859408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640859408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (727179648).

640859408 is an abundant number, since it is smaller than the sum of its proper divisors (813499888).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640859408 is a wasteful number, since it uses less digits than its factorization.

640859408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 952 (or 946 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 640859408 is about 25315.2011250158. The cubic root of 640859408 is about 862.1594406506.

The spelling of 640859408 in words is "six hundred forty million, eight hundred fifty-nine thousand, four hundred eight".