81261149 has 4 divisors (see below), whose sum is σ = 81297660. Its totient is φ = 81224640.

The previous prime is 81261143. The next prime is 81261163. The reversal of 81261149 is 94116218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3062500 + 78198649 = 1750^2 + 8843^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81261149 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81261143) 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 in 3 ways as a sum of consecutive naturals, for example, 14684 + ... + 19445.

It is an arithmetic number, because the mean of its divisors is an integer number (20324415).

Almost surely, 2^81261149 is an apocalyptic number.

It is an amenable number.

81261149 is a deficient number, since it is larger than the sum of its proper divisors (36511).

81261149 is a wasteful number, since it uses less digits than its factorization.

81261149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36510.

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

The square root of 81261149 is about 9014.4966026950. The cubic root of 81261149 is about 433.1393624306.

The spelling of 81261149 in words is "eighty-one million, two hundred sixty-one thousand, one hundred forty-nine".