81439893 has 24 divisors (see below), whose sum is σ = 121392128. Its totient is φ = 52581312.

The previous prime is 81439889. The next prime is 81439901. The reversal of 81439893 is 39893418.

It is not a de Polignac number, because 81439893 - 2² = 81439889 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81439493) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48321 + ... + 49977.

Almost surely, 2^81439893 is an apocalyptic number.

It is an amenable number.

81439893 is a deficient number, since it is larger than the sum of its proper divisors (39952235).

81439893 is a wasteful number, since it uses less digits than its factorization.

81439893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1833 (or 1830 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 81439893 is about 9024.4054097763. The cubic root of 81439893 is about 433.4567111541.

The spelling of 81439893 in words is "eighty-one million, four hundred thirty-nine thousand, eight hundred ninety-three".