7715921 has 4 divisors (see below), whose sum is σ = 7831152. Its totient is φ = 7600692.

The previous prime is 7715891. The next prime is 7715927. The reversal of 7715921 is 1295177.

7715921 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 7715921 - 2⁶ = 7715857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7715927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57515 + ... + 57648.

It is an arithmetic number, because the mean of its divisors is an integer number (1957788).

Almost surely, 2^7715921 is an apocalyptic number.

It is an amenable number.

7715921 is a deficient number, since it is larger than the sum of its proper divisors (115231).

7715921 is a wasteful number, since it uses less digits than its factorization.

7715921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115230.

The product of its digits is 4410, while the sum is 32.

The square root of 7715921 is about 2777.7546687928. The cubic root of 7715921 is about 197.6040876320.

The spelling of 7715921 in words is "seven million, seven hundred fifteen thousand, nine hundred twenty-one".