81582400 has 42 divisors (see below), whose sum is σ = 200747630. Its totient is φ = 32632320.

The previous prime is 81582383. The next prime is 81582401. The reversal of 81582400 is 428518.

It can be written as a sum of positive squares in 3 ways, for example, as 5683456 + 75898944 = 2384^2 + 8712^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81582401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 23895 + ... + 27094.

Almost surely, 2^81582400 is an apocalyptic number.

81582400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81582400 is an abundant number, since it is smaller than the sum of its proper divisors (119165230).

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

81582400 is a wasteful number, since it uses less digits than its factorization.

81582400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51011 (or 50996 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 81582400 is about 9032.2976036001. The cubic root of 81582400 is about 433.7093908447.

The spelling of 81582400 in words is "eighty-one million, five hundred eighty-two thousand, four hundred".