81243885 has 16 divisors (see below), whose sum is σ = 132194880. Its totient is φ = 42595200.

The previous prime is 81243881. The next prime is 81243893. The reversal of 81243885 is 58834218.

It is not a de Polignac number, because 81243885 - 2² = 81243881 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81243881) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45016 + ... + 46785.

It is an arithmetic number, because the mean of its divisors is an integer number (8262180).

Almost surely, 2^81243885 is an apocalyptic number.

It is an amenable number.

81243885 is a deficient number, since it is larger than the sum of its proper divisors (50950995).

81243885 is a wasteful number, since it uses less digits than its factorization.

81243885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91868.

The product of its digits is 61440, while the sum is 39.

The square root of 81243885 is about 9013.5389831076. The cubic root of 81243885 is about 433.1086866499.

It can be divided in two parts, 81243 and 885, that added together give a palindrome (82128).

The spelling of 81243885 in words is "eighty-one million, two hundred forty-three thousand, eight hundred eighty-five".