166312021 has 2 divisors, whose sum is σ = 166312022. Its totient is φ = 166312020.

The previous prime is 166312007. The next prime is 166312043. The reversal of 166312021 is 120213661.

It is an a-pointer prime, because the next prime (166312043) can be obtained adding 166312021 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116100625 + 50211396 = 10775^2 + 7086^2 .

It is an emirp because it is prime and its reverse (120213661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166312021 - 2⁵ = 166311989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 166311983 and 166312001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166312001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83156010 + 83156011.

It is an arithmetic number, because the mean of its divisors is an integer number (83156011).

Almost surely, 2^166312021 is an apocalyptic number.

It is an amenable number.

166312021 is a deficient number, since it is larger than the sum of its proper divisors (1).

166312021 is an equidigital number, since it uses as much as digits as its factorization.

166312021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 166312021 is about 12896.2018051828. The cubic root of 166312021 is about 549.9305928944.

Adding to 166312021 its reverse (120213661), we get a palindrome (286525682).

The spelling of 166312021 in words is "one hundred sixty-six million, three hundred twelve thousand, twenty-one".