640991201 has 4 divisors (see below), whose sum is σ = 674727600. Its totient is φ = 607254804.

The previous prime is 640991191. The next prime is 640991249. The reversal of 640991201 is 102199046.

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 not a de Polignac number, because 640991201 - 2¹⁸ = 640729057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640991251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16868171 + ... + 16868208.

It is an arithmetic number, because the mean of its divisors is an integer number (168681900).

Almost surely, 2^640991201 is an apocalyptic number.

It is an amenable number.

640991201 is a deficient number, since it is larger than the sum of its proper divisors (33736399).

640991201 is a wasteful number, since it uses less digits than its factorization.

640991201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33736398.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 640991201 is about 25317.8040319456. The cubic root of 640991201 is about 862.2185377472.

The spelling of 640991201 in words is "six hundred forty million, nine hundred ninety-one thousand, two hundred one".