81442740 has 96 divisors (see below), whose sum is σ = 241920000. Its totient is φ = 20414592.

The previous prime is 81442717. The next prime is 81442789. The reversal of 81442740 is 4724418.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 81442698 and 81442707.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 226681 + ... + 227039.

It is an arithmetic number, because the mean of its divisors is an integer number (2520000).

Almost surely, 2^81442740 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81442740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120960000).

81442740 is an abundant number, since it is smaller than the sum of its proper divisors (160477260).

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

81442740 is a wasteful number, since it uses less digits than its factorization.

81442740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 589 (or 587 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 30.

The square root of 81442740 is about 9024.5631473219. The cubic root of 81442740 is about 433.4617620648.

The spelling of 81442740 in words is "eighty-one million, four hundred forty-two thousand, seven hundred forty".