115781221 has 2 divisors, whose sum is σ = 115781222. Its totient is φ = 115781220.

The previous prime is 115781209. The next prime is 115781321. The reversal of 115781221 is 122187511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 97812100 + 17969121 = 9890^2 + 4239^2 .

It is a cyclic number.

It is not a de Polignac number, because 115781221 - 2⁵ = 115781189 is a prime.

It is a super-2 number, since 2×115781221² = 26810582272501682, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 115781221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (115781321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57890610 + 57890611.

It is an arithmetic number, because the mean of its divisors is an integer number (57890611).

Almost surely, 2^115781221 is an apocalyptic number.

It is an amenable number.

115781221 is a deficient number, since it is larger than the sum of its proper divisors (1).

115781221 is an equidigital number, since it uses as much as digits as its factorization.

115781221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1120, while the sum is 28.

The square root of 115781221 is about 10760.1682607662. The cubic root of 115781221 is about 487.3930982779.

The spelling of 115781221 in words is "one hundred fifteen million, seven hundred eighty-one thousand, two hundred twenty-one".