661115111 has 2 divisors, whose sum is σ = 661115112. Its totient is φ = 661115110.

The previous prime is 661115099. The next prime is 661115129. The reversal of 661115111 is 111511166.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661115111 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661115171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330557555 + 330557556.

It is an arithmetic number, because the mean of its divisors is an integer number (330557556).

Almost surely, 2^661115111 is an apocalyptic number.

661115111 is a deficient number, since it is larger than the sum of its proper divisors (1).

661115111 is an equidigital number, since it uses as much as digits as its factorization.

661115111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 180, while the sum is 23.

The square root of 661115111 is about 25712.1588164044. The cubic root of 661115111 is about 871.1488372463.

Adding to 661115111 its reverse (111511166), we get a palindrome (772626277).

The spelling of 661115111 in words is "six hundred sixty-one million, one hundred fifteen thousand, one hundred eleven".