640933066 has 4 divisors (see below), whose sum is σ = 961399602. Its totient is φ = 320466532.

The previous prime is 640933063. The next prime is 640933067. The reversal of 640933066 is 660339046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 588790225 + 52142841 = 24265^2 + 7221^2 .

It is not an unprimeable number, because it can be changed into a prime (640933063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160233265 + ... + 160233268.

Almost surely, 2^640933066 is an apocalyptic number.

640933066 is a deficient number, since it is larger than the sum of its proper divisors (320466536).

640933066 is a wasteful number, since it uses less digits than its factorization.

640933066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320466535.

The product of its (nonzero) digits is 69984, while the sum is 37.

The square root of 640933066 is about 25316.6559008096. The cubic root of 640933066 is about 862.1924705198.

The spelling of 640933066 in words is "six hundred forty million, nine hundred thirty-three thousand, sixty-six".