663691894 has 4 divisors (see below), whose sum is σ = 995537844. Its totient is φ = 331845946.

The previous prime is 663691867. The next prime is 663691937. The reversal of 663691894 is 498196366.

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

It is a super-2 number, since 2×663691894² = 880973860322614472, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165922972 + ... + 165922975.

It is an arithmetic number, because the mean of its divisors is an integer number (248884461).

Almost surely, 2^663691894 is an apocalyptic number.

663691894 is a deficient number, since it is larger than the sum of its proper divisors (331845950).

663691894 is a wasteful number, since it uses less digits than its factorization.

663691894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331845949.

The product of its digits is 1679616, while the sum is 52.

The square root of 663691894 is about 25762.2183439237. The cubic root of 663691894 is about 872.2791756488.

The spelling of 663691894 in words is "six hundred sixty-three million, six hundred ninety-one thousand, eight hundred ninety-four".