640809036 has 96 divisors (see below), whose sum is σ = 1904448000. Its totient is φ = 182533824.

The previous prime is 640809023. The next prime is 640809047. The reversal of 640809036 is 630908046.

640809036 is a `hidden beast` number, since 640 + 8 + 0 + 9 + 0 + 3 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 292995 + ... + 295173.

It is an arithmetic number, because the mean of its divisors is an integer number (19838000).

Almost surely, 2^640809036 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 640809036, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (952224000).

640809036 is an abundant number, since it is smaller than the sum of its proper divisors (1263638964).

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

640809036 is a wasteful number, since it uses less digits than its factorization.

640809036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2588 (or 2580 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640809036 is about 25314.2062091625. The cubic root of 640809036 is about 862.1368512794.

The spelling of 640809036 in words is "six hundred forty million, eight hundred nine thousand, thirty-six".