81243638 has 16 divisors (see below), whose sum is σ = 143039904. Its totient is φ = 33877440.

The previous prime is 81243607. The next prime is 81243661. The reversal of 81243638 is 83634218.

It is a happy number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81243598 and 81243607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77903 + ... + 78938.

It is an arithmetic number, because the mean of its divisors is an integer number (8939994).

Almost surely, 2^81243638 is an apocalyptic number.

81243638 is a deficient number, since it is larger than the sum of its proper divisors (61796266).

81243638 is a wasteful number, since it uses less digits than its factorization.

81243638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156887.

The product of its digits is 27648, while the sum is 35.

The square root of 81243638 is about 9013.5252814867. The cubic root of 81243638 is about 433.1082477329.

The spelling of 81243638 in words is "eighty-one million, two hundred forty-three thousand, six hundred thirty-eight".