81436849 has 4 divisors (see below), whose sum is σ = 87701236. Its totient is φ = 75172464.

The previous prime is 81436841. The next prime is 81436871. The reversal of 81436849 is 94863418.

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 3732624 + 77704225 = 1932^2 + 8815^2 .

It is a cyclic number.

It is not a de Polignac number, because 81436849 - 2³ = 81436841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81436841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3132174 + ... + 3132199.

It is an arithmetic number, because the mean of its divisors is an integer number (21925309).

Almost surely, 2^81436849 is an apocalyptic number.

It is an amenable number.

81436849 is a deficient number, since it is larger than the sum of its proper divisors (6264387).

81436849 is a wasteful number, since it uses less digits than its factorization.

81436849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6264386.

The product of its digits is 165888, while the sum is 43.

The square root of 81436849 is about 9024.2367544297. The cubic root of 81436849 is about 433.4513106122.

The spelling of 81436849 in words is "eighty-one million, four hundred thirty-six thousand, eight hundred forty-nine".