8921581 has 2 divisors, whose sum is σ = 8921582. Its totient is φ = 8921580.

The previous prime is 8921573. The next prime is 8921599. The reversal of 8921581 is 1851298.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6456681 + 2464900 = 2541^2 + 1570^2 .

It is a cyclic number.

It is not a de Polignac number, because 8921581 - 2³ = 8921573 is a prime.

It is a super-2 number, since 2×8921581² = 159189215079122, which contains 22 as substring.

8921581 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8924581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4460790 + 4460791.

It is an arithmetic number, because the mean of its divisors is an integer number (4460791).

Almost surely, 2^8921581 is an apocalyptic number.

It is an amenable number.

8921581 is a deficient number, since it is larger than the sum of its proper divisors (1).

8921581 is an equidigital number, since it uses as much as digits as its factorization.

8921581 is an evil number, because the sum of its binary digits is even.

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

The square root of 8921581 is about 2986.9015718634. The cubic root of 8921581 is about 207.4024780035.

The spelling of 8921581 in words is "eight million, nine hundred twenty-one thousand, five hundred eighty-one".