81367569 has 12 divisors (see below), whose sum is σ = 117744900. Its totient is φ = 54146304.

The previous prime is 81367553. The next prime is 81367579. The reversal of 81367569 is 96576318.

It is a happy number.

81367569 is a `hidden beast` number, since 81 + 3 + 6 + 7 + 569 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 15563025 + 65804544 = 3945^2 + 8112^2 .

It is not a de Polignac number, because 81367569 - 2⁴ = 81367553 is a prime.

It is a super-2 number, since 2×81367569² = 13241362569939522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81367579) 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 in 11 ways as a sum of consecutive naturals, for example, 2824 + ... + 13065.

It is an arithmetic number, because the mean of its divisors is an integer number (9812075).

Almost surely, 2^81367569 is an apocalyptic number.

It is an amenable number.

81367569 is a deficient number, since it is larger than the sum of its proper divisors (36377331).

81367569 is a wasteful number, since it uses less digits than its factorization.

81367569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16464 (or 16461 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 81367569 is about 9020.3973859249. The cubic root of 81367569 is about 433.3283604295.

The spelling of 81367569 in words is "eighty-one million, three hundred sixty-seven thousand, five hundred sixty-nine".