640837693 has 4 divisors (see below), whose sum is σ = 649863648. Its totient is φ = 631811740.

The previous prime is 640837663. The next prime is 640837709. The reversal of 640837693 is 396738046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640837693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640837663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4512871 + ... + 4513012.

It is an arithmetic number, because the mean of its divisors is an integer number (162465912).

Almost surely, 2^640837693 is an apocalyptic number.

It is an amenable number.

640837693 is a deficient number, since it is larger than the sum of its proper divisors (9025955).

640837693 is an equidigital number, since it uses as much as digits as its factorization.

640837693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9025954.

The product of its (nonzero) digits is 653184, while the sum is 46.

The square root of 640837693 is about 25314.7722288785. The cubic root of 640837693 is about 862.1497026834.

The spelling of 640837693 in words is "six hundred forty million, eight hundred thirty-seven thousand, six hundred ninety-three".