7921868921 has 4 divisors (see below), whose sum is σ = 7928064000. Its totient is φ = 7915673844.

The previous prime is 7921868893. The next prime is 7921868939. The reversal of 7921868921 is 1298681297.

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.

It is a cyclic number.

It is not a de Polignac number, because 7921868921 - 2¹⁴ = 7921852537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7921868221) 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, 3095621 + ... + 3098178.

It is an arithmetic number, because the mean of its divisors is an integer number (1982016000).

Almost surely, 2^7921868921 is an apocalyptic number.

It is an amenable number.

7921868921 is a deficient number, since it is larger than the sum of its proper divisors (6195079).

7921868921 is a wasteful number, since it uses less digits than its factorization.

7921868921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6195078.

The product of its digits is 870912, while the sum is 53.

The square root of 7921868921 is about 89004.8814447837. The cubic root of 7921868921 is about 1993.4677649301.

The spelling of 7921868921 in words is "seven billion, nine hundred twenty-one million, eight hundred sixty-eight thousand, nine hundred twenty-one".