661115129 has 2 divisors, whose sum is σ = 661115130. Its totient is φ = 661115128.

The previous prime is 661115111. The next prime is 661115167. The reversal of 661115129 is 921511166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 618865129 + 42250000 = 24877^2 + 6500^2 .

It is a cyclic number.

It is not a de Polignac number, because 661115129 - 2¹⁶ = 661049593 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661115095 and 661115104.

It is not a weakly prime, because it can be changed into another prime (661112129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330557564 + 330557565.

It is an arithmetic number, because the mean of its divisors is an integer number (330557565).

Almost surely, 2^661115129 is an apocalyptic number.

It is an amenable number.

661115129 is a deficient number, since it is larger than the sum of its proper divisors (1).

661115129 is an equidigital number, since it uses as much as digits as its factorization.

661115129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 32.

The square root of 661115129 is about 25712.1591664333. The cubic root of 661115129 is about 871.1488451525.

The spelling of 661115129 in words is "six hundred sixty-one million, one hundred fifteen thousand, one hundred twenty-nine".