645641870 has 16 divisors (see below), whose sum is σ = 1162613088. Its totient is φ = 258155040.

The previous prime is 645641839. The next prime is 645641891. The reversal of 645641870 is 78146546.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17327 + ... + 39893.

It is an arithmetic number, because the mean of its divisors is an integer number (72663318).

Almost surely, 2^645641870 is an apocalyptic number.

645641870 is a deficient number, since it is larger than the sum of its proper divisors (516971218).

645641870 is a wasteful number, since it uses less digits than its factorization.

645641870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25435.

The product of its (nonzero) digits is 161280, while the sum is 41.

The square root of 645641870 is about 25409.4838593782. The cubic root of 645641870 is about 864.2987712372.

The spelling of 645641870 in words is "six hundred forty-five million, six hundred forty-one thousand, eight hundred seventy".