7913721 has 8 divisors (see below), whose sum is σ = 11172384. Its totient is φ = 4965440.

The previous prime is 7913701. The next prime is 7913749. The reversal of 7913721 is 1273197.

7913721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 7913721 - 2⁶ = 7913657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7913701) 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, 77535 + ... + 77636.

It is an arithmetic number, because the mean of its divisors is an integer number (1396548).

Almost surely, 2^7913721 is an apocalyptic number.

It is an amenable number.

7913721 is a deficient number, since it is larger than the sum of its proper divisors (3258663).

7913721 is a wasteful number, since it uses less digits than its factorization.

7913721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155191.

The product of its digits is 2646, while the sum is 30.

The square root of 7913721 is about 2813.1336619507. The cubic root of 7913721 is about 199.2784079893.

The spelling of 7913721 in words is "seven million, nine hundred thirteen thousand, seven hundred twenty-one".