81912434 has 4 divisors (see below), whose sum is σ = 122868654. Its totient is φ = 40956216.

The previous prime is 81912427. The next prime is 81912449. The reversal of 81912434 is 43421918.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 51165409 + 30747025 = 7153^2 + 5545^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81912434.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20478107 + ... + 20478110.

Almost surely, 2^81912434 is an apocalyptic number.

81912434 is a deficient number, since it is larger than the sum of its proper divisors (40956220).

81912434 is a wasteful number, since it uses less digits than its factorization.

81912434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40956219.

The product of its digits is 6912, while the sum is 32.

The square root of 81912434 is about 9050.5488231377. The cubic root of 81912434 is about 434.2934476161.

The spelling of 81912434 in words is "eighty-one million, nine hundred twelve thousand, four hundred thirty-four".