81469440 has 336 divisors, whose sum is σ = 322024248. Its totient is φ = 18874368.

The previous prime is 81469433. The next prime is 81469441. The reversal of 81469440 is 4496418.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 61968384 + 19501056 = 7872^2 + 4416^2 .

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 = 81469395 and 81469404.

It is not an unprimeable number, because it can be changed into a prime (81469441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4792312 + ... + 4792328.

Almost surely, 2^81469440 is an apocalyptic number.

81469440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81469440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161012124).

81469440 is an abundant number, since it is smaller than the sum of its proper divisors (240554808).

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

81469440 is a wasteful number, since it uses less digits than its factorization.

81469440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 81469440 is about 9026.0423220811. The cubic root of 81469440 is about 433.5091252574.

The spelling of 81469440 in words is "eighty-one million, four hundred sixty-nine thousand, four hundred forty".