640355477 has 4 divisors (see below), whose sum is σ = 640572000. Its totient is φ = 640138956.

The previous prime is 640355459. The next prime is 640355479. The reversal of 640355477 is 774553046.

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 640355477 - 2¹² = 640351381 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 (640355479) 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 3 ways as a sum of consecutive naturals, for example, 103763 + ... + 109760.

It is an arithmetic number, because the mean of its divisors is an integer number (160143000).

Almost surely, 2^640355477 is an apocalyptic number.

It is an amenable number.

640355477 is a deficient number, since it is larger than the sum of its proper divisors (216523).

640355477 is a wasteful number, since it uses less digits than its factorization.

640355477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216522.

The product of its (nonzero) digits is 352800, while the sum is 41.

The square root of 640355477 is about 25305.2460371363. The cubic root of 640355477 is about 861.9333989775.

The spelling of 640355477 in words is "six hundred forty million, three hundred fifty-five thousand, four hundred seventy-seven".