663640566 has 16 divisors (see below), whose sum is σ = 1327551984. Its totient is φ = 221168384.

The previous prime is 663640541. The next prime is 663640567. The reversal of 663640566 is 665046366.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663640567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35470 + ... + 50846.

It is an arithmetic number, because the mean of its divisors is an integer number (82971999).

Almost surely, 2^663640566 is an apocalyptic number.

663640566 is an abundant number, since it is smaller than the sum of its proper divisors (663911418).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

663640566 is a wasteful number, since it uses less digits than its factorization.

663640566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22575.

The product of its (nonzero) digits is 466560, while the sum is 42.

The square root of 663640566 is about 25761.2221371580. Note that the first 3 decimals coincide. The cubic root of 663640566 is about 872.2566885580.

The spelling of 663640566 in words is "six hundred sixty-three million, six hundred forty thousand, five hundred sixty-six".