81541779919 has 8 divisors (see below), whose sum is σ = 81725184000. Its totient is φ = 81358431672.

The previous prime is 81541779901. The next prime is 81541779923. The reversal of 81541779919 is 91997714518.

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

It is a cyclic number.

It is not a de Polignac number, because 81541779919 - 2³³ = 72951845327 is a prime.

It is a super-2 number, since 2×81541779919² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81541779929) 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, 4531462 + ... + 4549420.

It is an arithmetic number, because the mean of its divisors is an integer number (10215648000).

Almost surely, 2^81541779919 is an apocalyptic number.

81541779919 is a deficient number, since it is larger than the sum of its proper divisors (183404081).

81541779919 is a wasteful number, since it uses less digits than its factorization.

81541779919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27917.

The product of its digits is 5715360, while the sum is 61.

The spelling of 81541779919 in words is "eighty-one billion, five hundred forty-one million, seven hundred seventy-nine thousand, nine hundred nineteen".