81741991 has 8 divisors (see below), whose sum is σ = 84460320. Its totient is φ = 79050528.

The previous prime is 81741983. The next prime is 81742021. The reversal of 81741991 is 19914718.

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 81741991 - 2³ = 81741983 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 (81741911) 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, 436 + ... + 12793.

It is an arithmetic number, because the mean of its divisors is an integer number (10557540).

Almost surely, 2^81741991 is an apocalyptic number.

81741991 is a deficient number, since it is larger than the sum of its proper divisors (2718329).

81741991 is a wasteful number, since it uses less digits than its factorization.

81741991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13433.

The product of its digits is 18144, while the sum is 40.

The square root of 81741991 is about 9041.1277504524. The cubic root of 81741991 is about 433.9920132036.

The spelling of 81741991 in words is "eighty-one million, seven hundred forty-one thousand, nine hundred ninety-one".