8521921 has 4 divisors (see below), whose sum is σ = 8528832. Its totient is φ = 8515012.

The previous prime is 8521907. The next prime is 8521939. The reversal of 8521921 is 1291258.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1291258 = 2 ⋅645629.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8521921 is a prime.

It is a Duffinian number.

8521921 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 8521921.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8521021) 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, 1045 + ... + 4258.

It is an arithmetic number, because the mean of its divisors is an integer number (2132208).

Almost surely, 2^8521921 is an apocalyptic number.

It is an amenable number.

8521921 is a deficient number, since it is larger than the sum of its proper divisors (6911).

8521921 is a wasteful number, since it uses less digits than its factorization.

8521921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6910.

The product of its digits is 1440, while the sum is 28.

The square root of 8521921 is about 2919.2329471969. The cubic root of 8521921 is about 204.2580436360.

The spelling of 8521921 in words is "eight million, five hundred twenty-one thousand, nine hundred twenty-one".