640215798 has 8 divisors (see below), whose sum is σ = 1280431608. Its totient is φ = 213405264.

The previous prime is 640215739. The next prime is 640215799. The reversal of 640215798 is 897512046.

It is a sphenic number, since it is the product of 3 distinct primes.

640215798 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640215799) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53351311 + ... + 53351322.

It is an arithmetic number, because the mean of its divisors is an integer number (160053951).

Almost surely, 2^640215798 is an apocalyptic number.

640215798 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640215798 is a wasteful number, since it uses less digits than its factorization.

640215798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106702638.

The product of its (nonzero) digits is 120960, while the sum is 42.

The square root of 640215798 is about 25302.4860043435. The cubic root of 640215798 is about 861.8707240236.

The spelling of 640215798 in words is "six hundred forty million, two hundred fifteen thousand, seven hundred ninety-eight".