8398921 has 2 divisors, whose sum is σ = 8398922. Its totient is φ = 8398920.

The previous prime is 8398913. The next prime is 8398927. The reversal of 8398921 is 1298938.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5198400 + 3200521 = 2280^2 + 1789^2 .

It is a cyclic number.

It is not a de Polignac number, because 8398921 - 2³ = 8398913 is a prime.

It is not a weakly prime, because it can be changed into another prime (8398927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4199460 + 4199461.

It is an arithmetic number, because the mean of its divisors is an integer number (4199461).

Almost surely, 2^8398921 is an apocalyptic number.

It is an amenable number.

8398921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8398921 is an equidigital number, since it uses as much as digits as its factorization.

8398921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 40.

The square root of 8398921 is about 2898.0891980752. The cubic root of 8398921 is about 203.2705670881.

The spelling of 8398921 in words is "eight million, three hundred ninety-eight thousand, nine hundred twenty-one".