7921997 has 4 divisors (see below), whose sum is σ = 7931040. Its totient is φ = 7912956.

The previous prime is 7921987. The next prime is 7921999. The reversal of 7921997 is 7991297.

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, and also an emirpimes, since its reverse is a distinct semiprime: 7991297 = 37 ⋅215981.

It is a cyclic number.

It is not a de Polignac number, because 7921997 - 2⁴ = 7921981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7921999) 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, 3047 + ... + 5012.

It is an arithmetic number, because the mean of its divisors is an integer number (1982760).

Almost surely, 2^7921997 is an apocalyptic number.

It is an amenable number.

7921997 is a deficient number, since it is larger than the sum of its proper divisors (9043).

7921997 is an equidigital number, since it uses as much as digits as its factorization.

7921997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9042.

The product of its digits is 71442, while the sum is 44.

The square root of 7921997 is about 2814.6042350569. The cubic root of 7921997 is about 199.3478508185.

The spelling of 7921997 in words is "seven million, nine hundred twenty-one thousand, nine hundred ninety-seven".