661111201 has 4 divisors (see below), whose sum is σ = 661166212. Its totient is φ = 661056192.

The previous prime is 661111193. The next prime is 661111207. The reversal of 661111201 is 102111166.

661111201 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 544989025 + 116122176 = 23345^2 + 10776^2 .

It is a cyclic number.

It is not a de Polignac number, because 661111201 - 2³ = 661111193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661111207) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 900 + ... + 36373.

It is an arithmetic number, because the mean of its divisors is an integer number (165291553).

Almost surely, 2^661111201 is an apocalyptic number.

It is an amenable number.

661111201 is a deficient number, since it is larger than the sum of its proper divisors (55011).

661111201 is a wasteful number, since it uses less digits than its factorization.

661111201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55010.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 661111201 is about 25712.0827822252. The cubic root of 661111201 is about 871.1471198456.

Adding to 661111201 its reverse (102111166), we get a palindrome (763222367).

The spelling of 661111201 in words is "six hundred sixty-one million, one hundred eleven thousand, two hundred one".