7638721 has 2 divisors, whose sum is σ = 7638722. Its totient is φ = 7638720.

The previous prime is 7638707. The next prime is 7638727. The reversal of 7638721 is 1278367.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5948721 + 1690000 = 2439^2 + 1300^2 .

It is a cyclic number.

It is not a de Polignac number, because 7638721 - 2⁵ = 7638689 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (7638727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3819360 + 3819361.

It is an arithmetic number, because the mean of its divisors is an integer number (3819361).

Almost surely, 2^7638721 is an apocalyptic number.

It is an amenable number.

7638721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7638721 is an equidigital number, since it uses as much as digits as its factorization.

7638721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 34.

The square root of 7638721 is about 2763.8236195532. The cubic root of 7638721 is about 196.9428489082.

The spelling of 7638721 in words is "seven million, six hundred thirty-eight thousand, seven hundred twenty-one".