6638721 has 8 divisors (see below), whose sum is σ = 9372384. Its totient is φ = 4165440.

The previous prime is 6638701. The next prime is 6638741. The reversal of 6638721 is 1278366.

It is an interprime number because it is at equal distance from previous prime (6638701) and next prime (6638741).

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

It is not a de Polignac number, because 6638721 - 2⁵ = 6638689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6638701) 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, 65035 + ... + 65136.

It is an arithmetic number, because the mean of its divisors is an integer number (1171548).

Almost surely, 2^6638721 is an apocalyptic number.

It is an amenable number.

6638721 is a deficient number, since it is larger than the sum of its proper divisors (2733663).

6638721 is a wasteful number, since it uses less digits than its factorization.

6638721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130191.

The product of its digits is 12096, while the sum is 33.

The square root of 6638721 is about 2576.5715592624. The cubic root of 6638721 is about 187.9438586703.

The spelling of 6638721 in words is "six million, six hundred thirty-eight thousand, seven hundred twenty-one".