661261225 has 27 divisors (see below), whose sum is σ = 848830437. Its totient is φ = 511008480.

The previous prime is 661261207. The next prime is 661261273. The reversal of 661261225 is 522162166.

The square root of 661261225 is 25715.

It is a perfect power (a square), and thus also a powerful number.

661261225 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 4 ways, for example, as 62773929 + 598487296 = 7923^2 + 24464^2 .

It is not a de Polignac number, because 661261225 - 2²⁷ = 527043497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4757206 + ... + 4757344.

Almost surely, 2^661261225 is an apocalyptic number.

661261225 is the 25715-th square number.

661261225 is the 12858-th centered octagonal number.

It is an amenable number.

661261225 is a deficient number, since it is larger than the sum of its proper divisors (187569212).

661261225 is an equidigital number, since it uses as much as digits as its factorization.

661261225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362 (or 181 counting only the distinct ones).

The product of its digits is 8640, while the sum is 31.

The cubic root of 661261225 is about 871.2130104707.

The spelling of 661261225 in words is "six hundred sixty-one million, two hundred sixty-one thousand, two hundred twenty-five".