661115 has 16 divisors (see below), whose sum is σ = 977088. Its totient is φ = 418176.

The previous prime is 661109. The next prime is 661117. The reversal of 661115 is 511166.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 661115 - 2⁴ = 661099 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 272 + ... + 1181.

It is an arithmetic number, because the mean of its divisors is an integer number (61068).

2⁶⁶¹¹¹⁵ is an apocalyptic number.

661115 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

661115 is a deficient number, since it is larger than the sum of its proper divisors (315973).

661115 is a wasteful number, since it uses less digits than its factorization.

661115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1478.

The product of its digits is 180, while the sum is 20.

The square root of 661115 is about 813.0897859400. The cubic root of 661115 is about 87.1148788492.

The spelling of 661115 in words is "six hundred sixty-one thousand, one hundred fifteen".