81974149 has 2 divisors, whose sum is σ = 81974150. Its totient is φ = 81974148.

The previous prime is 81974111. The next prime is 81974171. The reversal of 81974149 is 94147918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76300225 + 5673924 = 8735^2 + 2382^2 .

It is a cyclic number.

It is not a de Polignac number, because 81974149 - 2¹³ = 81965957 is a prime.

It is a super-2 number, since 2×81974149² = 13439522208548402, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81975149) 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, 40987074 + 40987075.

It is an arithmetic number, because the mean of its divisors is an integer number (40987075).

Almost surely, 2^81974149 is an apocalyptic number.

It is an amenable number.

81974149 is a deficient number, since it is larger than the sum of its proper divisors (1).

81974149 is an equidigital number, since it uses as much as digits as its factorization.

81974149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 81974149 is about 9053.9576429316. The cubic root of 81974149 is about 434.4024896358.

The spelling of 81974149 in words is "eighty-one million, nine hundred seventy-four thousand, one hundred forty-nine".