640378065 has 16 divisors (see below), whose sum is σ = 1043938368. Its totient is φ = 335090496.

The previous prime is 640378021. The next prime is 640378073. The reversal of 640378065 is 560873046.

It is not a de Polignac number, because 640378065 - 2⁶ = 640378001 is a prime.

It is a super-2 number, since 2×640378065² = 820168132266288450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 401959 + ... + 403548.

It is an arithmetic number, because the mean of its divisors is an integer number (65246148).

Almost surely, 2^640378065 is an apocalyptic number.

It is an amenable number.

640378065 is a deficient number, since it is larger than the sum of its proper divisors (403560303).

640378065 is a wasteful number, since it uses less digits than its factorization.

640378065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805568.

The product of its (nonzero) digits is 120960, while the sum is 39.

The square root of 640378065 is about 25305.6923438186. The cubic root of 640378065 is about 861.9435335165.

The spelling of 640378065 in words is "six hundred forty million, three hundred seventy-eight thousand, sixty-five".