115661009 has 2 divisors, whose sum is σ = 115661010. Its totient is φ = 115661008.

The previous prime is 115661003. The next prime is 115661011. The reversal of 115661009 is 900166511.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59830225 + 55830784 = 7735^2 + 7472^2 .

It is a cyclic number.

It is not a de Polignac number, because 115661009 - 2¹² = 115656913 is a prime.

It is a Sophie Germain prime.

Together with 115661011, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (115661003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57830504 + 57830505.

It is an arithmetic number, because the mean of its divisors is an integer number (57830505).

Almost surely, 2^115661009 is an apocalyptic number.

It is an amenable number.

115661009 is a deficient number, since it is larger than the sum of its proper divisors (1).

115661009 is an equidigital number, since it uses as much as digits as its factorization.

115661009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 115661009 is about 10754.5808379499. The cubic root of 115661009 is about 487.2243582240.

It can be divided in two parts, 1156 and 61009, that multiplied together give a square (70526404 = 8398²).

The spelling of 115661009 in words is "one hundred fifteen million, six hundred sixty-one thousand, nine".