81409213887 has 8 divisors (see below), whose sum is σ = 109274113200. Its totient is φ = 53908561920.

The previous prime is 81409213843. The next prime is 81409213889. The reversal of 81409213887 is 78831290418.

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

It is a de Polignac number, because none of the positive numbers 2^k-81409213887 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81409213889) 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, 91061314 + ... + 91062207.

It is an arithmetic number, because the mean of its divisors is an integer number (13659264150).

Almost surely, 2^81409213887 is an apocalyptic number.

81409213887 is a deficient number, since it is larger than the sum of its proper divisors (27864899313).

81409213887 is a wasteful number, since it uses less digits than its factorization.

81409213887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182123673.

The product of its (nonzero) digits is 774144, while the sum is 51.

It can be divided in two parts, 81409 and 213887, that added together give a triangular number (295296 = T₇₆₈).

The spelling of 81409213887 in words is "eighty-one billion, four hundred nine million, two hundred thirteen thousand, eight hundred eighty-seven".