81511471 has 8 divisors (see below), whose sum is σ = 85185504. Its totient is φ = 77848320.

The previous prime is 81511453. The next prime is 81511487. The reversal of 81511471 is 17411518.

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 81511471 - 2⁹ = 81510959 is a prime.

It is a super-3 number, since 3×81511471³ (a number of 25 digits) contains 333 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 (81511411) 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, 15175 + ... + 19831.

It is an arithmetic number, because the mean of its divisors is an integer number (10648188).

Almost surely, 2^81511471 is an apocalyptic number.

81511471 is a deficient number, since it is larger than the sum of its proper divisors (3674033).

81511471 is a wasteful number, since it uses less digits than its factorization.

81511471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5441.

The product of its digits is 1120, while the sum is 28.

The square root of 81511471 is about 9028.3703402109. The cubic root of 81511471 is about 433.5836631843.

Adding to 81511471 its reverse (17411518), we get a palindrome (98922989).

The spelling of 81511471 in words is "eighty-one million, five hundred eleven thousand, four hundred seventy-one".