81899542 has 4 divisors (see below), whose sum is σ = 122849316. Its totient is φ = 40949770.

The previous prime is 81899539. The next prime is 81899549. The reversal of 81899542 is 24599818.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 81899492 and 81899501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81899549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20474884 + ... + 20474887.

It is an arithmetic number, because the mean of its divisors is an integer number (30712329).

Almost surely, 2^81899542 is an apocalyptic number.

81899542 is a deficient number, since it is larger than the sum of its proper divisors (40949774).

81899542 is a wasteful number, since it uses less digits than its factorization.

81899542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40949773.

The product of its digits is 207360, while the sum is 46.

The square root of 81899542 is about 9049.8365731100. The cubic root of 81899542 is about 434.2706622887.

The spelling of 81899542 in words is "eighty-one million, eight hundred ninety-nine thousand, five hundred forty-two".