81139112 has 8 divisors (see below), whose sum is σ = 152135850. Its totient is φ = 40569552.

The previous prime is 81139111. The next prime is 81139133. The reversal of 81139112 is 21193118.

It can be written as a sum of positive squares in only one way, i.e., 80389156 + 749956 = 8966^2 + 866^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×81139112² = 13167110992297088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81139111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5071187 + ... + 5071202.

Almost surely, 2^81139112 is an apocalyptic number.

It is an amenable number.

81139112 is a deficient number, since it is larger than the sum of its proper divisors (70996738).

81139112 is a wasteful number, since it uses less digits than its factorization.

81139112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10142395 (or 10142391 counting only the distinct ones).

The product of its digits is 432, while the sum is 26.

The square root of 81139112 is about 9007.7251290212. The cubic root of 81139112 is about 432.9224259973.

The spelling of 81139112 in words is "eighty-one million, one hundred thirty-nine thousand, one hundred twelve".