166712021 has 4 divisors (see below), whose sum is σ = 190528032. Its totient is φ = 142896012.

The previous prime is 166712009. The next prime is 166712069. The reversal of 166712021 is 120217661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120217661 = 257 ⋅467773.

It is not a de Polignac number, because 166712021 - 2⁶ = 166711957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166712321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11907995 + ... + 11908008.

It is an arithmetic number, because the mean of its divisors is an integer number (47632008).

Almost surely, 2^166712021 is an apocalyptic number.

It is an amenable number.

166712021 is a deficient number, since it is larger than the sum of its proper divisors (23816011).

166712021 is an equidigital number, since it uses as much as digits as its factorization.

166712021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23816010.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 166712021 is about 12911.7009336493. The cubic root of 166712021 is about 550.3711225247.

Adding to 166712021 its reverse (120217661), we get a palindrome (286929682).

The spelling of 166712021 in words is "one hundred sixty-six million, seven hundred twelve thousand, twenty-one".