166021731 has 16 divisors (see below), whose sum is σ = 248997920. Its totient is φ = 110679696.

The previous prime is 166021729. The next prime is 166021741. The reversal of 166021731 is 137120661.

166021731 is a `hidden beast` number, since 16 + 602 + 17 + 31 = 666.

166021731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 166021731 - 2¹ = 166021729 is a prime.

It is a super-2 number, since 2×166021731² = 55126430328472722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 166021695 and 166021704.

It is not an unprimeable number, because it can be changed into a prime (166021721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35770 + ... + 40143.

It is an arithmetic number, because the mean of its divisors is an integer number (15562370).

Almost surely, 2^166021731 is an apocalyptic number.

166021731 is a deficient number, since it is larger than the sum of its proper divisors (82976189).

166021731 is an frugal number, since it uses more digits than its factorization.

166021731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75934 (or 75916 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 166021731 is about 12884.9420254808. The cubic root of 166021731 is about 549.6104470183.

The spelling of 166021731 in words is "one hundred sixty-six million, twenty-one thousand, seven hundred thirty-one".