166505381 has 12 divisors (see below), whose sum is σ = 194420160. Its totient is φ = 142180920.

The previous prime is 166505369. The next prime is 166505399. The reversal of 166505381 is 183505661.

It is not a de Polignac number, because 166505381 - 2¹⁰ = 166504357 is a prime.

It is a super-2 number, since 2×166505381² = 55448083803910322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166505321) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7010 + ... + 19548.

It is an arithmetic number, because the mean of its divisors is an integer number (16201680).

Almost surely, 2^166505381 is an apocalyptic number.

It is an amenable number.

166505381 is a deficient number, since it is larger than the sum of its proper divisors (27914779).

166505381 is a wasteful number, since it uses less digits than its factorization.

166505381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12824 (or 12817 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 35.

The square root of 166505381 is about 12903.6964083940. The cubic root of 166505381 is about 550.1436330103.

The spelling of 166505381 in words is "one hundred sixty-six million, five hundred five thousand, three hundred eighty-one".