661636611 has 6 divisors (see below), whose sum is σ = 955697340. Its totient is φ = 441091068.

The previous prime is 661636603. The next prime is 661636621. The reversal of 661636611 is 116636166.

It is a happy number.

661636611 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 36 + 611 = 666.

It is not a de Polignac number, because 661636611 - 2³ = 661636603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661636621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36757581 + ... + 36757598.

It is an arithmetic number, because the mean of its divisors is an integer number (159282890).

Almost surely, 2^661636611 is an apocalyptic number.

661636611 is a deficient number, since it is larger than the sum of its proper divisors (294060729).

661636611 is a wasteful number, since it uses less digits than its factorization.

661636611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73515185 (or 73515182 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 661636611 is about 25722.2979338939. The cubic root of 661636611 is about 871.3778365582.

The spelling of 661636611 in words is "six hundred sixty-one million, six hundred thirty-six thousand, six hundred eleven".