81911742 has 16 divisors (see below), whose sum is σ = 178716672. Its totient is φ = 24821720.

The previous prime is 81911719. The next prime is 81911743. The reversal of 81911742 is 24711918.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81911743) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 620478 + ... + 620609.

It is an arithmetic number, because the mean of its divisors is an integer number (11169792).

Almost surely, 2^81911742 is an apocalyptic number.

81911742 is an abundant number, since it is smaller than the sum of its proper divisors (96804930).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81911742 is a wasteful number, since it uses less digits than its factorization.

81911742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1241103.

The product of its digits is 4032, while the sum is 33.

The square root of 81911742 is about 9050.5105933312. The cubic root of 81911742 is about 434.2922246357.

It can be divided in two parts, 819 and 11742, that added together give a triangular number (12561 = T₁₅₈).

The spelling of 81911742 in words is "eighty-one million, nine hundred eleven thousand, seven hundred forty-two".