166779521 has 2 divisors, whose sum is σ = 166779522. Its totient is φ = 166779520.

The previous prime is 166779517. The next prime is 166779527. The reversal of 166779521 is 125977661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107412496 + 59367025 = 10364^2 + 7705^2 .

It is a cyclic number.

It is not a de Polignac number, because 166779521 - 2² = 166779517 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (166779527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83389760 + 83389761.

It is an arithmetic number, because the mean of its divisors is an integer number (83389761).

Almost surely, 2^166779521 is an apocalyptic number.

It is an amenable number.

166779521 is a deficient number, since it is larger than the sum of its proper divisors (1).

166779521 is an equidigital number, since it uses as much as digits as its factorization.

166779521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 158760, while the sum is 44.

The square root of 166779521 is about 12914.3145772433. The cubic root of 166779521 is about 550.4453923900.

The spelling of 166779521 in words is "one hundred sixty-six million, seven hundred seventy-nine thousand, five hundred twenty-one".