7881581 has 2 divisors, whose sum is σ = 7881582. Its totient is φ = 7881580.

The previous prime is 7881569. The next prime is 7881583. The reversal of 7881581 is 1851887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4141225 + 3740356 = 2035^2 + 1934^2 .

It is a cyclic number.

It is not a de Polignac number, because 7881581 - 2¹⁰ = 7880557 is a prime.

It is a super-2 number, since 2×7881581² = 124238638119122, which contains 22 as substring.

Together with 7881583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7881583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3940790 + 3940791.

It is an arithmetic number, because the mean of its divisors is an integer number (3940791).

Almost surely, 2^7881581 is an apocalyptic number.

It is an amenable number.

7881581 is a deficient number, since it is larger than the sum of its proper divisors (1).

7881581 is an equidigital number, since it uses as much as digits as its factorization.

7881581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17920, while the sum is 38.

The square root of 7881581 is about 2807.4153593653. The cubic root of 7881581 is about 199.0082654412.

The spelling of 7881581 in words is "seven million, eight hundred eighty-one thousand, five hundred eighty-one".