81439487 has 4 divisors (see below), whose sum is σ = 81549840. Its totient is φ = 81329136.

The previous prime is 81439483. The next prime is 81439493. The reversal of 81439487 is 78493418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78493418 = 2 ⋅39246709.

It is a cyclic number.

It is not a de Polignac number, because 81439487 - 2² = 81439483 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 (81439483) 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, 54062 + ... + 55547.

It is an arithmetic number, because the mean of its divisors is an integer number (20387460).

Almost surely, 2^81439487 is an apocalyptic number.

81439487 is a deficient number, since it is larger than the sum of its proper divisors (110353).

81439487 is a wasteful number, since it uses less digits than its factorization.

81439487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110352.

The product of its digits is 193536, while the sum is 44.

The square root of 81439487 is about 9024.3829151915. The cubic root of 81439487 is about 433.4559908531.

The spelling of 81439487 in words is "eighty-one million, four hundred thirty-nine thousand, four hundred eighty-seven".