166718421 has 12 divisors (see below), whose sum is σ = 251286048. Its totient is φ = 106313064.

The previous prime is 166718401. The next prime is 166718441. The reversal of 166718421 is 124817661.

It is a happy number.

166718421 is a `hidden beast` number, since 166 + 71 + 8 + 421 = 666.

It is an interprime number because it is at equal distance from previous prime (166718401) and next prime (166718441).

It is not a de Polignac number, because 166718421 - 2⁵ = 166718389 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166718401) 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, 402495 + ... + 402908.

It is an arithmetic number, because the mean of its divisors is an integer number (20940504).

Almost surely, 2^166718421 is an apocalyptic number.

It is an amenable number.

166718421 is a deficient number, since it is larger than the sum of its proper divisors (84567627).

166718421 is a wasteful number, since it uses less digits than its factorization.

166718421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805432 (or 805429 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 166718421 is about 12911.9487684857. The cubic root of 166718421 is about 550.3781652684.

The spelling of 166718421 in words is "one hundred sixty-six million, seven hundred eighteen thousand, four hundred twenty-one".