661111611 has 16 divisors (see below), whose sum is σ = 912046080. Its totient is φ = 425525760.

The previous prime is 661111603. The next prime is 661111639. The reversal of 661111611 is 116111166.

It is not a de Polignac number, because 661111611 - 2³ = 661111603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661111411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32731 + ... + 48923.

It is an arithmetic number, because the mean of its divisors is an integer number (57002880).

Almost surely, 2^661111611 is an apocalyptic number.

661111611 is a deficient number, since it is larger than the sum of its proper divisors (250934469).

661111611 is a wasteful number, since it uses less digits than its factorization.

661111611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16666.

The product of its digits is 216, while the sum is 24.

The square root of 661111611 is about 25712.0907551292. The cubic root of 661111611 is about 871.1472999314.

Adding to 661111611 its reverse (116111166), we get a palindrome (777222777).

The spelling of 661111611 in words is "six hundred sixty-one million, one hundred eleven thousand, six hundred eleven".