640537773 has 4 divisors (see below), whose sum is σ = 854050368. Its totient is φ = 427025180.

The previous prime is 640537769. The next prime is 640537783. The reversal of 640537773 is 377735046.

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 640537773 - 2² = 640537769 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640537783) 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, 106756293 + ... + 106756298.

It is an arithmetic number, because the mean of its divisors is an integer number (213512592).

Almost surely, 2^640537773 is an apocalyptic number.

It is an amenable number.

640537773 is a deficient number, since it is larger than the sum of its proper divisors (213512595).

640537773 is a wasteful number, since it uses less digits than its factorization.

640537773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213512594.

The product of its (nonzero) digits is 370440, while the sum is 42.

The square root of 640537773 is about 25308.8477216961. The cubic root of 640537773 is about 862.0151827724.

The spelling of 640537773 in words is "six hundred forty million, five hundred thirty-seven thousand, seven hundred seventy-three".