166391525 has 6 divisors (see below), whose sum is σ = 206325522. Its totient is φ = 133113200.

The previous prime is 166391521. The next prime is 166391543. The reversal of 166391525 is 525193661.

It can be written as a sum of positive squares in 3 ways, for example, as 1705636 + 164685889 = 1306^2 + 12833^2 .

It is not a de Polignac number, because 166391525 - 2² = 166391521 is a prime.

It is a super-2 number, since 2×166391525² = 55372279183651250, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166391521) 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, 3327806 + ... + 3327855.

It is an arithmetic number, because the mean of its divisors is an integer number (34387587).

Almost surely, 2^166391525 is an apocalyptic number.

It is an amenable number.

166391525 is a deficient number, since it is larger than the sum of its proper divisors (39933997).

166391525 is an equidigital number, since it uses as much as digits as its factorization.

166391525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6655671 (or 6655666 counting only the distinct ones).

The product of its digits is 48600, while the sum is 38.

The square root of 166391525 is about 12899.2838948525. The cubic root of 166391525 is about 550.0182087635.

The spelling of 166391525 in words is "one hundred sixty-six million, three hundred ninety-one thousand, five hundred twenty-five".