640654265 has 8 divisors (see below), whose sum is σ = 814007880. Its totient is φ = 482374912.

The previous prime is 640654253. The next prime is 640654279. The reversal of 640654265 is 562456046.

It can be written as a sum of positive squares in 4 ways, for example, as 33327529 + 607326736 = 5773^2 + 24644^2 .

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 640654265 - 2¹⁸ = 640392121 is a prime.

It is a Curzon 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, 3768470 + ... + 3768639.

It is an arithmetic number, because the mean of its divisors is an integer number (101750985).

Almost surely, 2^640654265 is an apocalyptic number.

It is an amenable number.

640654265 is a deficient number, since it is larger than the sum of its proper divisors (173353615).

640654265 is a wasteful number, since it uses less digits than its factorization.

640654265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7537131.

The product of its (nonzero) digits is 172800, while the sum is 38.

The square root of 640654265 is about 25311.1490256764. The cubic root of 640654265 is about 862.0674366701.

The spelling of 640654265 in words is "six hundred forty million, six hundred fifty-four thousand, two hundred sixty-five".