81333437 has 4 divisors (see below), whose sum is σ = 83531676. Its totient is φ = 79135200.

The previous prime is 81333431. The next prime is 81333493. The reversal of 81333437 is 73433318.

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 47623801 + 33709636 = 6901^2 + 5806^2 .

It is a cyclic number.

It is not a de Polignac number, because 81333437 - 2¹⁴ = 81317053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81333431) 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, 1099064 + ... + 1099137.

It is an arithmetic number, because the mean of its divisors is an integer number (20882919).

Almost surely, 2^81333437 is an apocalyptic number.

It is an amenable number.

81333437 is a deficient number, since it is larger than the sum of its proper divisors (2198239).

81333437 is a wasteful number, since it uses less digits than its factorization.

81333437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2198238.

The product of its digits is 18144, while the sum is 32.

The square root of 81333437 is about 9018.5052530893. The cubic root of 81333437 is about 433.2677612155.

The spelling of 81333437 in words is "eighty-one million, three hundred thirty-three thousand, four hundred thirty-seven".