7919921 has 2 divisors, whose sum is σ = 7919922. Its totient is φ = 7919920.

The previous prime is 7919893. The next prime is 7919939. The reversal of 7919921 is 1299197.

7919921 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4906225 + 3013696 = 2215^2 + 1736^2 .

It is a cyclic number.

It is not a de Polignac number, because 7919921 - 2¹⁸ = 7657777 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (7919971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3959960 + 3959961.

It is an arithmetic number, because the mean of its divisors is an integer number (3959961).

Almost surely, 2^7919921 is an apocalyptic number.

It is an amenable number.

7919921 is a deficient number, since it is larger than the sum of its proper divisors (1).

7919921 is an equidigital number, since it uses as much as digits as its factorization.

7919921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10206, while the sum is 38.

The square root of 7919921 is about 2814.2354201452. The cubic root of 7919921 is about 199.3304359212.

The spelling of 7919921 in words is "seven million, nine hundred nineteen thousand, nine hundred twenty-one".