115155721 has 2 divisors, whose sum is σ = 115155722. Its totient is φ = 115155720.

The previous prime is 115155707. The next prime is 115155737. The reversal of 115155721 is 127551511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64176121 + 50979600 = 8011^2 + 7140^2 .

It is a cyclic number.

It is not a de Polignac number, because 115155721 - 2¹¹ = 115153673 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 115155721.

It is not a weakly prime, because it can be changed into another prime (115155221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57577860 + 57577861.

It is an arithmetic number, because the mean of its divisors is an integer number (57577861).

Almost surely, 2^115155721 is an apocalyptic number.

It is an amenable number.

115155721 is a deficient number, since it is larger than the sum of its proper divisors (1).

115155721 is an equidigital number, since it uses as much as digits as its factorization.

115155721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1750, while the sum is 28.

The square root of 115155721 is about 10731.0633676258. The cubic root of 115155721 is about 486.5138104943.

The spelling of 115155721 in words is "one hundred fifteen million, one hundred fifty-five thousand, seven hundred twenty-one".