640786477 has 4 divisors (see below), whose sum is σ = 648506880. Its totient is φ = 633066076.

The previous prime is 640786453. The next prime is 640786511. The reversal of 640786477 is 774687046.

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 640786477 - 2¹⁵ = 640753709 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640786477.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640786177) 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, 3860077 + ... + 3860242.

It is an arithmetic number, because the mean of its divisors is an integer number (162126720).

Almost surely, 2^640786477 is an apocalyptic number.

It is an amenable number.

640786477 is a deficient number, since it is larger than the sum of its proper divisors (7720403).

640786477 is an equidigital number, since it uses as much as digits as its factorization.

640786477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7720402.

The product of its (nonzero) digits is 1580544, while the sum is 49.

The square root of 640786477 is about 25313.7606253990. The cubic root of 640786477 is about 862.1267342906.

The spelling of 640786477 in words is "six hundred forty million, seven hundred eighty-six thousand, four hundred seventy-seven".