6636721 has 8 divisors (see below), whose sum is σ = 8168384. Its totient is φ = 5250960.

The previous prime is 6636709. The next prime is 6636767. The reversal of 6636721 is 1276366.

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

It is not a de Polignac number, because 6636721 - 2⁵ = 6636689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6636701) 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, 36375 + ... + 36556.

It is an arithmetic number, because the mean of its divisors is an integer number (1021048).

Almost surely, 2^6636721 is an apocalyptic number.

It is an amenable number.

6636721 is a deficient number, since it is larger than the sum of its proper divisors (1531663).

6636721 is a wasteful number, since it uses less digits than its factorization.

6636721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72951.

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

The square root of 6636721 is about 2576.1834173832. The cubic root of 6636721 is about 187.9249832740.

The spelling of 6636721 in words is "six million, six hundred thirty-six thousand, seven hundred twenty-one".