166917188025 has 135 divisors (see below), whose sum is σ = 359945581149. Its totient is φ = 76246168320.

The previous prime is 166917187949. The next prime is 166917188027. The reversal of 166917188025 is 520881719661.

It is a happy number.

The square root of 166917188025 is 408555.

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

166917188025 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 51352545321 + 115564642704 = 226611^2 + 339948^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is not a de Polignac number, because 166917188025 - 2¹⁹ = 166916663737 is a prime.

It is a super-2 number, since 2×166917188025² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166917188027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 128694177 + ... + 128695473.

Almost surely, 2^166917188025 is an apocalyptic number.

166917188025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

166917188025 is the 408555-th square number.

166917188025 is the 204278-th centered octagonal number.

It is an amenable number.

166917188025 is an abundant number, since it is smaller than the sum of its proper divisors (193028393124).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

166917188025 is an frugal number, since it uses more digits than its factorization.

166917188025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2630 (or 1312 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 54.

The spelling of 166917188025 in words is "one hundred sixty-six billion, nine hundred seventeen million, one hundred eighty-eight thousand, twenty-five".