640487933 has 2 divisors, whose sum is σ = 640487934. Its totient is φ = 640487932.

The previous prime is 640487927. The next prime is 640487959. The reversal of 640487933 is 339784046.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 372412804 + 268075129 = 19298^2 + 16373^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640487933 is a prime.

It is a super-2 number, since 2×640487933² = 820449584637224978, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640487963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320243966 + 320243967.

It is an arithmetic number, because the mean of its divisors is an integer number (320243967).

Almost surely, 2^640487933 is an apocalyptic number.

It is an amenable number.

640487933 is a deficient number, since it is larger than the sum of its proper divisors (1).

640487933 is an equidigital number, since it uses as much as digits as its factorization.

640487933 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 44.

The square root of 640487933 is about 25307.8630666439. The cubic root of 640487933 is about 861.9928245016.

The spelling of 640487933 in words is "six hundred forty million, four hundred eighty-seven thousand, nine hundred thirty-three".