81919719447 has 8 divisors (see below), whose sum is σ = 110086342656. Its totient is φ = 54183121272.

The previous prime is 81919719433. The next prime is 81919719467. The reversal of 81919719447 is 74491791918.

It is a happy number.

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

It is not a de Polignac number, because 81919719447 - 2⁸ = 81919719191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81919719467) 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, 107505813 + ... + 107506574.

It is an arithmetic number, because the mean of its divisors is an integer number (13760792832).

Almost surely, 2^81919719447 is an apocalyptic number.

81919719447 is a deficient number, since it is larger than the sum of its proper divisors (28166623209).

81919719447 is a wasteful number, since it uses less digits than its factorization.

81919719447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215012517.

The product of its digits is 4572288, while the sum is 60.

The spelling of 81919719447 in words is "eighty-one billion, nine hundred nineteen million, seven hundred nineteen thousand, four hundred forty-seven".