640662899 has 4 divisors (see below), whose sum is σ = 644962800. Its totient is φ = 636363000.

The previous prime is 640662889. The next prime is 640662923. The reversal of 640662899 is 998266046.

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 640662899 - 2²⁰ = 639614323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640662839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2149727 + ... + 2150024.

It is an arithmetic number, because the mean of its divisors is an integer number (161240700).

Almost surely, 2^640662899 is an apocalyptic number.

640662899 is a deficient number, since it is larger than the sum of its proper divisors (4299901).

640662899 is a wasteful number, since it uses less digits than its factorization.

640662899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4299900.

The product of its (nonzero) digits is 1119744, while the sum is 50.

The square root of 640662899 is about 25311.3195823529. The cubic root of 640662899 is about 862.0713093033.

The spelling of 640662899 in words is "six hundred forty million, six hundred sixty-two thousand, eight hundred ninety-nine".