81870111 has 12 divisors (see below), whose sum is σ = 120261960. Its totient is φ = 53654640.

The previous prime is 81870109. The next prime is 81870119. The reversal of 81870111 is 11107818.

It is not a de Polignac number, because 81870111 - 2¹ = 81870109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81870119) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 76560 + ... + 77621.

It is an arithmetic number, because the mean of its divisors is an integer number (10021830).

Almost surely, 2^81870111 is an apocalyptic number.

81870111 is a deficient number, since it is larger than the sum of its proper divisors (38391849).

81870111 is a wasteful number, since it uses less digits than its factorization.

81870111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154246 (or 154243 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 27.

The square root of 81870111 is about 9048.2103755384. The cubic root of 81870111 is about 434.2186369626.

Adding to 81870111 its reverse (11107818), we get a palindrome (92977929).

The spelling of 81870111 in words is "eighty-one million, eight hundred seventy thousand, one hundred eleven".