640020965 has 8 divisors (see below), whose sum is σ = 770799480. Its totient is φ = 510167232.

The previous prime is 640020961. The next prime is 640020973. The reversal of 640020965 is 569020046.

It can be written as a sum of positive squares in 4 ways, for example, as 1852321 + 638168644 = 1361^2 + 25262^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640020965 - 2² = 640020961 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640020961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 229670 + ... + 232439.

It is an arithmetic number, because the mean of its divisors is an integer number (96349935).

Almost surely, 2^640020965 is an apocalyptic number.

It is an amenable number.

640020965 is a deficient number, since it is larger than the sum of its proper divisors (130778515).

640020965 is a wasteful number, since it uses less digits than its factorization.

640020965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462391.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 640020965 is about 25298.6356351484. The cubic root of 640020965 is about 861.7832858524.

The spelling of 640020965 in words is "six hundred forty million, twenty thousand, nine hundred sixty-five".