81935139 has 64 divisors (see below), whose sum is σ = 135991296. Its totient is φ = 43200000.

The previous prime is 81935123. The next prime is 81935141. The reversal of 81935139 is 93153918.

It is not a de Polignac number, because 81935139 - 2⁴ = 81935123 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 81935097 and 81935106.

It is not an unprimeable number, because it can be changed into a prime (81935939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 811189 + ... + 811289.

It is an arithmetic number, because the mean of its divisors is an integer number (2124864).

Almost surely, 2^81935139 is an apocalyptic number.

81935139 is a deficient number, since it is larger than the sum of its proper divisors (54056157).

81935139 is a wasteful number, since it uses less digits than its factorization.

81935139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220.

The product of its digits is 29160, while the sum is 39.

The square root of 81935139 is about 9051.8030800499. The cubic root of 81935139 is about 434.3335706325. Note that the first 3 decimals are identical.

The spelling of 81935139 in words is "eighty-one million, nine hundred thirty-five thousand, one hundred thirty-nine".