168820409 has 2 divisors, whose sum is σ = 168820410. Its totient is φ = 168820408.

The previous prime is 168820357. The next prime is 168820429. The reversal of 168820409 is 904028861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 120934009 + 47886400 = 10997^2 + 6920^2 .

It is a cyclic number.

It is not a de Polignac number, because 168820409 - 2¹² = 168816313 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (168820429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84410204 + 84410205.

It is an arithmetic number, because the mean of its divisors is an integer number (84410205).

Almost surely, 2^168820409 is an apocalyptic number.

It is an amenable number.

168820409 is a deficient number, since it is larger than the sum of its proper divisors (1).

168820409 is an equidigital number, since it uses as much as digits as its factorization.

168820409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 168820409 is about 12993.0908178154. The cubic root of 168820409 is about 552.6815701017.

The spelling of 168820409 in words is "one hundred sixty-eight million, eight hundred twenty thousand, four hundred nine".