640252106 has 24 divisors (see below), whose sum is σ = 1046997900. Its totient is φ = 293494656.

The previous prime is 640252099. The next prime is 640252133. The reversal of 640252106 is 601252046.

It can be written as a sum of positive squares in 6 ways, for example, as 123099025 + 517153081 = 11095^2 + 22741^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44006 + ... + 56718.

Almost surely, 2^640252106 is an apocalyptic number.

640252106 is a deficient number, since it is larger than the sum of its proper divisors (406745794).

640252106 is a wasteful number, since it uses less digits than its factorization.

640252106 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12890 (or 12877 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 640252106 is about 25303.2034730783. The cubic root of 640252106 is about 861.8870165564.

The spelling of 640252106 in words is "six hundred forty million, two hundred fifty-two thousand, one hundred six".