8821921 has 4 divisors (see below), whose sum is σ = 8832132. Its totient is φ = 8811712.

The previous prime is 8821919. The next prime is 8821927. The reversal of 8821921 is 1291288.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1852321 + 6969600 = 1361^2 + 2640^2 .

It is a cyclic number.

It is not a de Polignac number, because 8821921 - 2¹ = 8821919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8821927) 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, 3676 + ... + 5581.

It is an arithmetic number, because the mean of its divisors is an integer number (2208033).

Almost surely, 2^8821921 is an apocalyptic number.

It is an amenable number.

8821921 is a deficient number, since it is larger than the sum of its proper divisors (10211).

8821921 is an equidigital number, since it uses as much as digits as its factorization.

8821921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10210.

The product of its digits is 2304, while the sum is 31.

The square root of 8821921 is about 2970.1718805483. The cubic root of 8821921 is about 206.6273098254.

The spelling of 8821921 in words is "eight million, eight hundred twenty-one thousand, nine hundred twenty-one".