166220381 has 2 divisors, whose sum is σ = 166220382. Its totient is φ = 166220380.

The previous prime is 166220359. The next prime is 166220387. The reversal of 166220381 is 183022661.

166220381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 117917881 + 48302500 = 10859^2 + 6950^2 .

It is a cyclic number.

It is not a de Polignac number, because 166220381 - 2¹⁰ = 166219357 is a prime.

It is a super-2 number, since 2×166220381² = 55258430119570322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166220387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83110190 + 83110191.

It is an arithmetic number, because the mean of its divisors is an integer number (83110191).

Almost surely, 2^166220381 is an apocalyptic number.

It is an amenable number.

166220381 is a deficient number, since it is larger than the sum of its proper divisors (1).

166220381 is an equidigital number, since it uses as much as digits as its factorization.

166220381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 166220381 is about 12892.6483315105. The cubic root of 166220381 is about 549.8295681293.

The spelling of 166220381 in words is "one hundred sixty-six million, two hundred twenty thousand, three hundred eighty-one".