645902670 has 128 divisors (see below), whose sum is σ = 1868562432. Its totient is φ = 139766400.

The previous prime is 645902669. The next prime is 645902683. The reversal of 645902670 is 76209546.

It is a super-2 number, since 2×645902670² = 834380518226257800, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 304915 + ... + 307025.

It is an arithmetic number, because the mean of its divisors is an integer number (14598144).

Almost surely, 2^645902670 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645902670, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (934281216).

645902670 is an abundant number, since it is smaller than the sum of its proper divisors (1222659762).

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

645902670 is a wasteful number, since it uses less digits than its factorization.

645902670 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2206.

The product of its (nonzero) digits is 90720, while the sum is 39.

The square root of 645902670 is about 25414.6152833365. The cubic root of 645902670 is about 864.4151302624.

The spelling of 645902670 in words is "six hundred forty-five million, nine hundred two thousand, six hundred seventy".