81813744 has 30 divisors (see below), whose sum is σ = 228965256. Its totient is φ = 27271200.

The previous prime is 81813731. The next prime is 81813761. The reversal of 81813744 is 44731818.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81813699 and 81813708.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 283932 + ... + 284219.

Almost surely, 2^81813744 is an apocalyptic number.

It is an amenable number.

81813744 is an abundant number, since it is smaller than the sum of its proper divisors (147151512).

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

81813744 is a wasteful number, since it uses less digits than its factorization.

81813744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568165 (or 568156 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 81813744 is about 9045.0950243765. The cubic root of 81813744 is about 434.1189619170.

The spelling of 81813744 in words is "eighty-one million, eight hundred thirteen thousand, seven hundred forty-four".