640236737 has 8 divisors (see below), whose sum is σ = 736360896. Its totient is φ = 545278032.

The previous prime is 640236721. The next prime is 640236743. The reversal of 640236737 is 737632046.

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 640236737 - 2⁴ = 640236721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640236737.

It is not an unprimeable number, because it can be changed into a prime (640236797) by changing a digit.

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, 290183 + ... + 292380.

It is an arithmetic number, because the mean of its divisors is an integer number (92045112).

Almost surely, 2^640236737 is an apocalyptic number.

It is an amenable number.

640236737 is a deficient number, since it is larger than the sum of its proper divisors (96124159).

640236737 is a wasteful number, since it uses less digits than its factorization.

640236737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 582727.

The product of its (nonzero) digits is 127008, while the sum is 38.

The square root of 640236737 is about 25302.8997745318. The cubic root of 640236737 is about 861.8801200816.

The spelling of 640236737 in words is "six hundred forty million, two hundred thirty-six thousand, seven hundred thirty-seven".