8491621 has 2 divisors, whose sum is σ = 8491622. Its totient is φ = 8491620.

The previous prime is 8491591. The next prime is 8491643. The reversal of 8491621 is 1261948.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8491396 + 225 = 2914^2 + 15^2 .

It is a cyclic number.

It is not a de Polignac number, because 8491621 - 2⁵ = 8491589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8491121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4245810 + 4245811.

It is an arithmetic number, because the mean of its divisors is an integer number (4245811).

Almost surely, 2^8491621 is an apocalyptic number.

It is an amenable number.

8491621 is a deficient number, since it is larger than the sum of its proper divisors (1).

8491621 is an equidigital number, since it uses as much as digits as its factorization.

8491621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 31.

The square root of 8491621 is about 2914.0386064704. The cubic root of 8491621 is about 204.0156738566.

The spelling of 8491621 in words is "eight million, four hundred ninety-one thousand, six hundred twenty-one".