81265687 has 4 divisors (see below), whose sum is σ = 81398016. Its totient is φ = 81133360.

The previous prime is 81265673. The next prime is 81265699. The reversal of 81265687 is 78656218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78656218 = 2 ⋅39328109.

It is a cyclic number.

It is not a de Polignac number, because 81265687 - 2¹¹ = 81263639 is a prime.

It is a super-2 number, since 2×81265687² = 13208223767163938, 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 (81265487) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65239 + ... + 66472.

It is an arithmetic number, because the mean of its divisors is an integer number (20349504).

Almost surely, 2^81265687 is an apocalyptic number.

81265687 is a deficient number, since it is larger than the sum of its proper divisors (132329).

81265687 is a wasteful number, since it uses less digits than its factorization.

81265687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132328.

The product of its digits is 161280, while the sum is 43.

The square root of 81265687 is about 9014.7483048613. The cubic root of 81265687 is about 433.1474251185.

The spelling of 81265687 in words is "eighty-one million, two hundred sixty-five thousand, six hundred eighty-seven".