662728721 has 4 divisors (see below), whose sum is σ = 697609200. Its totient is φ = 627848244.

The previous prime is 662728681. The next prime is 662728741. The reversal of 662728721 is 127827266.

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 a de Polignac number, because none of the positive numbers 2^k-662728721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (662728741) 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, 17440211 + ... + 17440248.

It is an arithmetic number, because the mean of its divisors is an integer number (174402300).

Almost surely, 2^662728721 is an apocalyptic number.

It is an amenable number.

662728721 is a deficient number, since it is larger than the sum of its proper divisors (34880479).

662728721 is a wasteful number, since it uses less digits than its factorization.

662728721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34880478.

The product of its digits is 112896, while the sum is 41.

The square root of 662728721 is about 25743.5180385277. The cubic root of 662728721 is about 871.8570106316.

The spelling of 662728721 in words is "six hundred sixty-two million, seven hundred twenty-eight thousand, seven hundred twenty-one".