640533630 has 64 divisors (see below), whose sum is σ = 1679470848. Its totient is φ = 155055360.

The previous prime is 640533629. The next prime is 640533631. The reversal of 640533630 is 36335046.

It is an interprime number because it is at equal distance from previous prime (640533629) and next prime (640533631).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640533631) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 392877 + ... + 394503.

It is an arithmetic number, because the mean of its divisors is an integer number (26241732).

Almost surely, 2^640533630 is an apocalyptic number.

640533630 is an abundant number, since it is smaller than the sum of its proper divisors (1038937218).

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

640533630 is a wasteful number, since it uses less digits than its factorization.

640533630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2841.

The product of its (nonzero) digits is 19440, while the sum is 30.

The square root of 640533630 is about 25308.7658727169. The cubic root of 640533630 is about 862.0133242629.

Adding to 640533630 its reverse (36335046), we get a palindrome (676868676).

The spelling of 640533630 in words is "six hundred forty million, five hundred thirty-three thousand, six hundred thirty".