166821841 has 2 divisors, whose sum is σ = 166821842. Its totient is φ = 166821840.

The previous prime is 166821827. The next prime is 166821859. The reversal of 166821841 is 148128661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136890000 + 29931841 = 11700^2 + 5471^2 .

It is an emirp because it is prime and its reverse (148128661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166821841 - 2⁷ = 166821713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166821841.

It is not a weakly prime, because it can be changed into another prime (166821871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83410920 + 83410921.

It is an arithmetic number, because the mean of its divisors is an integer number (83410921).

Almost surely, 2^166821841 is an apocalyptic number.

It is an amenable number.

166821841 is a deficient number, since it is larger than the sum of its proper divisors (1).

166821841 is an equidigital number, since it uses as much as digits as its factorization.

166821841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18432, while the sum is 37.

The square root of 166821841 is about 12915.9529652287. The cubic root of 166821841 is about 550.4919466248.

The spelling of 166821841 in words is "one hundred sixty-six million, eight hundred twenty-one thousand, eight hundred forty-one".