663006721 has 8 divisors (see below), whose sum is σ = 716665320. Its totient is φ = 609727872.

The previous prime is 663006719. The next prime is 663006781. The reversal of 663006721 is 127600366.

It can be written as a sum of positive squares in 4 ways, for example, as 104346225 + 558660496 = 10215^2 + 23636^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 663006721 - 2¹ = 663006719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663006781) 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, 91300 + ... + 98293.

It is an arithmetic number, because the mean of its divisors is an integer number (89583165).

Almost surely, 2^663006721 is an apocalyptic number.

It is an amenable number.

663006721 is a deficient number, since it is larger than the sum of its proper divisors (53658599).

663006721 is a wasteful number, since it uses less digits than its factorization.

663006721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189875.

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 663006721 is about 25748.9168898422. The cubic root of 663006721 is about 871.9789018161.

The spelling of 663006721 in words is "six hundred sixty-three million, six thousand, seven hundred twenty-one".