661725 has 36 divisors (see below), whose sum is σ = 1262196. Its totient is φ = 330240.

The previous prime is 661721. The next prime is 661741. The reversal of 661725 is 527166.

661725 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 6 ways, for example, as 39204 + 622521 = 198^2 + 789^2 .

It is not a de Polignac number, because 661725 - 2² = 661721 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an Ulam number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661721) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3739 + ... + 3911.

It is an arithmetic number, because the mean of its divisors is an integer number (35061).

2⁶⁶¹⁷²⁵ is an apocalyptic number.

It is an amenable number.

661725 is a deficient number, since it is larger than the sum of its proper divisors (600471).

661725 is a wasteful number, since it uses less digits than its factorization.

661725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206 (or 198 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 661725 is about 813.4648117774. The cubic root of 661725 is about 87.1416637709.

The spelling of 661725 in words is "six hundred sixty-one thousand, seven hundred twenty-five".