81667539 has 12 divisors (see below), whose sum is σ = 118210872. Its totient is φ = 54331200.

The previous prime is 81667519. The next prime is 81667543. The reversal of 81667539 is 93576618.

It is a happy number.

It is not a de Polignac number, because 81667539 - 2¹² = 81663443 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81667494 and 81667503.

It is not an unprimeable number, because it can be changed into a prime (81667519) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4822 + ... + 13659.

It is an arithmetic number, because the mean of its divisors is an integer number (9850906).

Almost surely, 2^81667539 is an apocalyptic number.

81667539 is a deficient number, since it is larger than the sum of its proper divisors (36543333).

81667539 is a wasteful number, since it uses less digits than its factorization.

81667539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18978 (or 18975 counting only the distinct ones).

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

The square root of 81667539 is about 9037.0094057714. The cubic root of 81667539 is about 433.8602107362.

The spelling of 81667539 in words is "eighty-one million, six hundred sixty-seven thousand, five hundred thirty-nine".