81471744 has 90 divisors (see below), whose sum is σ = 242995830. Its totient is φ = 27150336.

The previous prime is 81471739. The next prime is 81471749. The reversal of 81471744 is 44717418.

It is an interprime number because it is at equal distance from previous prime (81471739) and next prime (81471749).

It can be written as a sum of positive squares in only one way, i.e., 56070144 + 25401600 = 7488^2 + 5040^2 .

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 = 81471699 and 81471708.

It is not an unprimeable number, because it can be changed into a prime (81471749) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 18772 + ... + 22700.

Almost surely, 2^81471744 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 81471744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121497915).

81471744 is an abundant number, since it is smaller than the sum of its proper divisors (161524086).

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

81471744 is an equidigital number, since it uses as much as digits as its factorization.

81471744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3957 (or 3934 counting only the distinct ones).

The product of its digits is 25088, while the sum is 36.

The square root of 81471744 is about 9026.1699518677. The cubic root of 81471744 is about 433.5132118434.

It can be divided in two parts, 81471 and 744, that added together give a triangular number (82215 = T₄₀₅).

The spelling of 81471744 in words is "eighty-one million, four hundred seventy-one thousand, seven hundred forty-four".