81581071 has 8 divisors (see below), whose sum is σ = 95843664. Its totient is φ = 68459520.

The previous prime is 81581053. The next prime is 81581081. The reversal of 81581071 is 17018518.

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 81581071 - 2¹¹ = 81579023 is a prime.

It is a super-2 number, since 2×81581071² = 13310942291014082, which 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 (81581051) 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, 285106 + ... + 285391.

It is an arithmetic number, because the mean of its divisors is an integer number (11980458).

Almost surely, 2^81581071 is an apocalyptic number.

81581071 is a deficient number, since it is larger than the sum of its proper divisors (14262593).

81581071 is a wasteful number, since it uses less digits than its factorization.

81581071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 570521.

The product of its (nonzero) digits is 2240, while the sum is 31.

The square root of 81581071 is about 9032.2240339797. The cubic root of 81581071 is about 433.7070357497.

Adding to 81581071 its reverse (17018518), we get a palindrome (98599589).

It can be divided in two parts, 8158 and 1071, that added together give a palindrome (9229).

The spelling of 81581071 in words is "eighty-one million, five hundred eighty-one thousand, seventy-one".