640726165 has 8 divisors (see below), whose sum is σ = 776057760. Its totient is φ = 507790032.

The previous prime is 640726133. The next prime is 640726171. The reversal of 640726165 is 561627046.

It is a happy number.

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 640726165 - 2⁵ = 640726133 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 598275 + ... + 599344.

It is an arithmetic number, because the mean of its divisors is an integer number (97007220).

Almost surely, 2^640726165 is an apocalyptic number.

It is an amenable number.

640726165 is a deficient number, since it is larger than the sum of its proper divisors (135331595).

640726165 is a wasteful number, since it uses less digits than its factorization.

640726165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1197731.

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 640726165 is about 25312.5693085471. The cubic root of 640726165 is about 862.0996851248.

The spelling of 640726165 in words is "six hundred forty million, seven hundred twenty-six thousand, one hundred sixty-five".