7791921 has 6 divisors (see below), whose sum is σ = 11255010. Its totient is φ = 5194608.

The previous prime is 7791911. The next prime is 7791929. The reversal of 7791921 is 1291977.

It can be written as a sum of positive squares in only one way, i.e., 4410000 + 3381921 = 2100^2 + 1839^2 .

It is not a de Polignac number, because 7791921 - 2⁶ = 7791857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7791929) 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 5 ways as a sum of consecutive naturals, for example, 432876 + ... + 432893.

It is an arithmetic number, because the mean of its divisors is an integer number (1875835).

Almost surely, 2^7791921 is an apocalyptic number.

It is an amenable number.

7791921 is a deficient number, since it is larger than the sum of its proper divisors (3463089).

7791921 is a wasteful number, since it uses less digits than its factorization.

7791921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 865775 (or 865772 counting only the distinct ones).

The product of its digits is 7938, while the sum is 36.

The square root of 7791921 is about 2791.4012610157. The cubic root of 7791921 is about 198.2507536227.

The spelling of 7791921 in words is "seven million, seven hundred ninety-one thousand, nine hundred twenty-one".