81251111 has 8 divisors (see below), whose sum is σ = 85327584. Its totient is φ = 77220000.

The previous prime is 81251077. The next prime is 81251113. The reversal of 81251111 is 11115218.

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 81251111 - 2²² = 77056807 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81251113) 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, 7640 + ... + 14861.

It is an arithmetic number, because the mean of its divisors is an integer number (10665948).

Almost surely, 2^81251111 is an apocalyptic number.

81251111 is a deficient number, since it is larger than the sum of its proper divisors (4076473).

81251111 is a wasteful number, since it uses less digits than its factorization.

81251111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22681.

The product of its digits is 80, while the sum is 20.

The square root of 81251111 is about 9013.9398156411. The cubic root of 81251111 is about 433.1215267982.

Adding to 81251111 its reverse (11115218), we get a palindrome (92366329).

The spelling of 81251111 in words is "eighty-one million, two hundred fifty-one thousand, one hundred eleven".