640698026 has 8 divisors (see below), whose sum is σ = 979180164. Its totient is φ = 314304640.

The previous prime is 640698017. The next prime is 640698043. The reversal of 640698026 is 620896046.

It can be written as a sum of positive squares in 2 ways, for example, as 609349225 + 31348801 = 24685^2 + 5599^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3022055 + ... + 3022266.

Almost surely, 2^640698026 is an apocalyptic number.

640698026 is a deficient number, since it is larger than the sum of its proper divisors (338482138).

640698026 is a wasteful number, since it uses less digits than its factorization.

640698026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6044376.

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 640698026 is about 25312.0134718675. The cubic root of 640698026 is about 862.0870645600.

The spelling of 640698026 in words is "six hundred forty million, six hundred ninety-eight thousand, twenty-six".