640250491 has 4 divisors (see below), whose sum is σ = 640325800. Its totient is φ = 640175184.

The previous prime is 640250489. The next prime is 640250503. The reversal of 640250491 is 194052046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640250491 - 2¹ = 640250489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640250431) 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, 23001 + ... + 42538.

It is an arithmetic number, because the mean of its divisors is an integer number (160081450).

Almost surely, 2^640250491 is an apocalyptic number.

640250491 is a deficient number, since it is larger than the sum of its proper divisors (75309).

640250491 is an equidigital number, since it uses as much as digits as its factorization.

640250491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75308.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 640250491 is about 25303.1715601029. The cubic root of 640250491 is about 861.8862918686.

The spelling of 640250491 in words is "six hundred forty million, two hundred fifty thousand, four hundred ninety-one".