181421609 has 2 divisors, whose sum is σ = 181421610. Its totient is φ = 181421608.

The previous prime is 181421587. The next prime is 181421621. The reversal of 181421609 is 906124181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162690025 + 18731584 = 12755^2 + 4328^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181421609 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (181421689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90710804 + 90710805.

It is an arithmetic number, because the mean of its divisors is an integer number (90710805).

Almost surely, 2^181421609 is an apocalyptic number.

It is an amenable number.

181421609 is a deficient number, since it is larger than the sum of its proper divisors (1).

181421609 is an equidigital number, since it uses as much as digits as its factorization.

181421609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 181421609 is about 13469.2839082113. The cubic root of 181421609 is about 566.1041493219.

The spelling of 181421609 in words is "one hundred eighty-one million, four hundred twenty-one thousand, six hundred nine".