166420861 has 2 divisors, whose sum is σ = 166420862. Its totient is φ = 166420860.

The previous prime is 166420841. The next prime is 166420883. The reversal of 166420861 is 168024661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 158608836 + 7812025 = 12594^2 + 2795^2 .

It is a cyclic number.

It is not a de Polignac number, because 166420861 - 2⁹ = 166420349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166420811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83210430 + 83210431.

It is an arithmetic number, because the mean of its divisors is an integer number (83210431).

Almost surely, 2^166420861 is an apocalyptic number.

It is an amenable number.

166420861 is a deficient number, since it is larger than the sum of its proper divisors (1).

166420861 is an equidigital number, since it uses as much as digits as its factorization.

166420861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 166420861 is about 12900.4209621237. The cubic root of 166420861 is about 550.0505308946.

It can be divided in two parts, 166420 and 861, that added together give a square (167281 = 409²).

The spelling of 166420861 in words is "one hundred sixty-six million, four hundred twenty thousand, eight hundred sixty-one".