663978 has 16 divisors (see below), whose sum is σ = 1517760. Its totient is φ = 189696.

The previous prime is 663977. The next prime is 663979. The reversal of 663978 is 879366.

It is an interprime number because it is at equal distance from previous prime (663977) and next prime (663979).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 663978.

It is not an unprimeable number, because it can be changed into a prime (663973) 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, 7863 + ... + 7946.

It is an arithmetic number, because the mean of its divisors is an integer number (94860).

2⁶⁶³⁹⁷⁸ is an apocalyptic number.

663978 is an abundant number, since it is smaller than the sum of its proper divisors (853782).

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

663978 is a wasteful number, since it uses less digits than its factorization.

663978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15821.

The product of its digits is 54432, while the sum is 39.

The square root of 663978 is about 814.8484521676. The cubic root of 663978 is about 87.2404499089.

The spelling of 663978 in words is "six hundred sixty-three thousand, nine hundred seventy-eight".