640791000 has 256 divisors, whose sum is σ = 2256508800. Its totient is φ = 170294400.

The previous prime is 640790993. The next prime is 640791001. The reversal of 640791000 is 197046.

640791000 is a `hidden beast` number, since 640 + 7 + 9 + 10 + 0 + 0 = 666.

It is a super-2 number, since 2×640791000² = 821226211362000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640791001) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2186854 + ... + 2187146.

Almost surely, 2^640791000 is an apocalyptic number.

640791000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640791000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1128254400).

640791000 is an abundant number, since it is smaller than the sum of its proper divisors (1615717800).

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

640791000 is an equidigital number, since it uses as much as digits as its factorization.

640791000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335 (or 303 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 640791000 is about 25313.8499640019. The cubic root of 640791000 is about 862.1287627302.

The spelling of 640791000 in words is "six hundred forty million, seven hundred ninety-one thousand".