661636225 has 6 divisors (see below), whose sum is σ = 820428950. Its totient is φ = 529308960.

The previous prime is 661636211. The next prime is 661636253. The reversal of 661636225 is 522636166.

661636225 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 992016 + 660644209 = 996^2 + 25703^2 .

It is not a de Polignac number, because 661636225 - 2⁷ = 661636097 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13232700 + ... + 13232749.

Almost surely, 2^661636225 is an apocalyptic number.

It is an amenable number.

661636225 is a deficient number, since it is larger than the sum of its proper divisors (158792725).

661636225 is a wasteful number, since it uses less digits than its factorization.

661636225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26465459 (or 26465454 counting only the distinct ones).

The product of its digits is 77760, while the sum is 37.

The square root of 661636225 is about 25722.2904306751. The cubic root of 661636225 is about 871.3776671037.

The spelling of 661636225 in words is "six hundred sixty-one million, six hundred thirty-six thousand, two hundred twenty-five".