81439887 has 8 divisors (see below), whose sum is σ = 109306240. Its totient is φ = 53933400.

The previous prime is 81439867. The next prime is 81439889. The reversal of 81439887 is 78893418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81439887 - 2¹⁹ = 80915599 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 (81439889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89437 + ... + 90342.

It is an arithmetic number, because the mean of its divisors is an integer number (13663280).

Almost surely, 2^81439887 is an apocalyptic number.

81439887 is a deficient number, since it is larger than the sum of its proper divisors (27866353).

81439887 is a wasteful number, since it uses less digits than its factorization.

81439887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179933.

The product of its digits is 387072, while the sum is 48.

The square root of 81439887 is about 9024.4050773444. The cubic root of 81439887 is about 433.4567005093.

The spelling of 81439887 in words is "eighty-one million, four hundred thirty-nine thousand, eight hundred eighty-seven".