81722149 has 2 divisors, whose sum is σ = 81722150. Its totient is φ = 81722148.

The previous prime is 81722129. The next prime is 81722153. The reversal of 81722149 is 94122718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76912900 + 4809249 = 8770^2 + 2193^2 .

It is a cyclic number.

It is not a de Polignac number, because 81722149 - 2⁵ = 81722117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81722119) 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, 40861074 + 40861075.

It is an arithmetic number, because the mean of its divisors is an integer number (40861075).

Almost surely, 2^81722149 is an apocalyptic number.

It is an amenable number.

81722149 is a deficient number, since it is larger than the sum of its proper divisors (1).

81722149 is an equidigital number, since it uses as much as digits as its factorization.

81722149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 34.

The square root of 81722149 is about 9040.0303649933. The cubic root of 81722149 is about 433.9568947116.

The spelling of 81722149 in words is "eighty-one million, seven hundred twenty-two thousand, one hundred forty-nine".