645998790 has 16 divisors (see below), whose sum is σ = 1550397168. Its totient is φ = 172266336.

The previous prime is 645998789. The next prime is 645998831. The reversal of 645998790 is 97899546.

It is a self number, because there is not a number n which added to its sum of digits gives 645998790.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10766617 + ... + 10766676.

It is an arithmetic number, because the mean of its divisors is an integer number (96899823).

Almost surely, 2^645998790 is an apocalyptic number.

645998790 is an abundant number, since it is smaller than the sum of its proper divisors (904398378).

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

645998790 is a wasteful number, since it uses less digits than its factorization.

645998790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21533303.

The product of its (nonzero) digits is 4898880, while the sum is 57.

The square root of 645998790 is about 25416.5062508599. The cubic root of 645998790 is about 864.4580074454.

The spelling of 645998790 in words is "six hundred forty-five million, nine hundred ninety-eight thousand, seven hundred ninety".