81224139 has 12 divisors (see below), whose sum is σ = 111310584. Its totient is φ = 52683264.

The previous prime is 81224137. The next prime is 81224141. The reversal of 81224139 is 93142218.

It is an interprime number because it is at equal distance from previous prime (81224137) and next prime (81224141).

It is not a de Polignac number, because 81224139 - 2¹ = 81224137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81224137) 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, 5782 + ... + 13995.

It is an arithmetic number, because the mean of its divisors is an integer number (9275882).

Almost surely, 2^81224139 is an apocalyptic number.

81224139 is a deficient number, since it is larger than the sum of its proper divisors (30086445).

81224139 is a wasteful number, since it uses less digits than its factorization.

81224139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19854 (or 19817 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 81224139 is about 9012.4435643171. The cubic root of 81224139 is about 433.0735953645.

The spelling of 81224139 in words is "eighty-one million, two hundred twenty-four thousand, one hundred thirty-nine".