7923721 has 4 divisors (see below), whose sum is σ = 8533252. Its totient is φ = 7314192.

The previous prime is 7923719. The next prime is 7923731. The reversal of 7923721 is 1273297.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1273297 = 739 ⋅1723.

It can be written as a sum of positive squares in 2 ways, for example, as 741321 + 7182400 = 861^2 + 2680^2 .

It is a cyclic number.

It is not a de Polignac number, because 7923721 - 2¹ = 7923719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7923731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 304746 + ... + 304771.

It is an arithmetic number, because the mean of its divisors is an integer number (2133313).

Almost surely, 2^7923721 is an apocalyptic number.

It is an amenable number.

7923721 is a deficient number, since it is larger than the sum of its proper divisors (609531).

7923721 is a wasteful number, since it uses less digits than its factorization.

7923721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609530.

The product of its digits is 5292, while the sum is 31.

The square root of 7923721 is about 2814.9104781502. The cubic root of 7923721 is about 199.3623105887.

The spelling of 7923721 in words is "seven million, nine hundred twenty-three thousand, seven hundred twenty-one".