81415139 has 16 divisors (see below), whose sum is σ = 90091008. Its totient is φ = 73104672.

The previous prime is 81415121. The next prime is 81415141. The reversal of 81415139 is 93151418.

It is a cyclic number.

It is not a de Polignac number, because 81415139 - 2¹⁶ = 81349603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81415189) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 138404 + ... + 138990.

It is an arithmetic number, because the mean of its divisors is an integer number (5630688).

Almost surely, 2^81415139 is an apocalyptic number.

81415139 is a deficient number, since it is larger than the sum of its proper divisors (8675869).

81415139 is a wasteful number, since it uses less digits than its factorization.

81415139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 874.

The product of its digits is 4320, while the sum is 32.

The square root of 81415139 is about 9023.0338024414. The cubic root of 81415139 is about 433.4127897034.

The spelling of 81415139 in words is "eighty-one million, four hundred fifteen thousand, one hundred thirty-nine".