645088990 has 64 divisors (see below), whose sum is σ = 1436916096. Its totient is φ = 203046912.

The previous prime is 645088973. The next prime is 645089009. The reversal of 645088990 is 99880546.

It is a happy number.

It is a super-2 number, since 2×645088990² = 832279610038440200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 173794 + ... + 177466.

It is an arithmetic number, because the mean of its divisors is an integer number (22451814).

Almost surely, 2^645088990 is an apocalyptic number.

645088990 is an abundant number, since it is smaller than the sum of its proper divisors (791827106).

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

645088990 is a wasteful number, since it uses less digits than its factorization.

645088990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3893.

The product of its (nonzero) digits is 622080, while the sum is 49.

The square root of 645088990 is about 25398.6021268888. The cubic root of 645088990 is about 864.0519935775.

The spelling of 645088990 in words is "six hundred forty-five million, eighty-eight thousand, nine hundred ninety".