663644557 has 4 divisors (see below), whose sum is σ = 667716160. Its totient is φ = 659572956.

The previous prime is 663644549. The next prime is 663644563. The reversal of 663644557 is 755446366.

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 663644557 - 2³ = 663644549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663644537) 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, 2035557 + ... + 2035882.

It is an arithmetic number, because the mean of its divisors is an integer number (166929040).

Almost surely, 2^663644557 is an apocalyptic number.

It is an amenable number.

663644557 is a deficient number, since it is larger than the sum of its proper divisors (4071603).

663644557 is a wasteful number, since it uses less digits than its factorization.

663644557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4071602.

The product of its digits is 1814400, while the sum is 46.

The square root of 663644557 is about 25761.2995984286. The cubic root of 663644557 is about 872.2584370795.

The spelling of 663644557 in words is "six hundred sixty-three million, six hundred forty-four thousand, five hundred fifty-seven".