166344821 has 4 divisors (see below), whose sum is σ = 166572492. Its totient is φ = 166117152.

The previous prime is 166344817. The next prime is 166344823. The reversal of 166344821 is 128443661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 128443661 = 23 ⋅5584507.

It can be written as a sum of positive squares in 2 ways, for example, as 164198596 + 2146225 = 12814^2 + 1465^2 .

It is a cyclic number.

It is not a de Polignac number, because 166344821 - 2² = 166344817 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 (166344823) 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, 112736 + ... + 114201.

It is an arithmetic number, because the mean of its divisors is an integer number (41643123).

Almost surely, 2^166344821 is an apocalyptic number.

It is an amenable number.

166344821 is a deficient number, since it is larger than the sum of its proper divisors (227671).

166344821 is an equidigital number, since it uses as much as digits as its factorization.

166344821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227670.

The product of its digits is 27648, while the sum is 35.

The square root of 166344821 is about 12897.4734347468. The cubic root of 166344821 is about 549.9667428926.

The spelling of 166344821 in words is "one hundred sixty-six million, three hundred forty-four thousand, eight hundred twenty-one".