7639921 has 2 divisors, whose sum is σ = 7639922. Its totient is φ = 7639920.

The previous prime is 7639913. The next prime is 7639927. The reversal of 7639921 is 1299367.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7639696 + 225 = 2764^2 + 15^2 .

It is an emirp because it is prime and its reverse (1299367) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7639921 - 2³ = 7639913 is a prime.

It is not a weakly prime, because it can be changed into another prime (7639927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3819960 + 3819961.

It is an arithmetic number, because the mean of its divisors is an integer number (3819961).

Almost surely, 2^7639921 is an apocalyptic number.

It is an amenable number.

7639921 is a deficient number, since it is larger than the sum of its proper divisors (1).

7639921 is an equidigital number, since it uses as much as digits as its factorization.

7639921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20412, while the sum is 37.

The square root of 7639921 is about 2764.0407015817. The cubic root of 7639921 is about 196.9531612386.

The spelling of 7639921 in words is "seven million, six hundred thirty-nine thousand, nine hundred twenty-one".