8158921 has 4 divisors (see below), whose sum is σ = 8422144. Its totient is φ = 7895700.

The previous prime is 8158919. The next prime is 8158967. The reversal of 8158921 is 1298518.

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 not a de Polignac number, because 8158921 - 2¹ = 8158919 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8158021) 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, 131565 + ... + 131626.

It is an arithmetic number, because the mean of its divisors is an integer number (2105536).

Almost surely, 2^8158921 is an apocalyptic number.

It is an amenable number.

8158921 is a deficient number, since it is larger than the sum of its proper divisors (263223).

8158921 is a wasteful number, since it uses less digits than its factorization.

8158921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263222.

The product of its digits is 5760, while the sum is 34.

The square root of 8158921 is about 2856.3825023970. The cubic root of 8158921 is about 201.3156677798.

The spelling of 8158921 in words is "eight million, one hundred fifty-eight thousand, nine hundred twenty-one".