81415400 has 96 divisors (see below), whose sum is σ = 215611200. Its totient is φ = 28300800.

The previous prime is 81415391. The next prime is 81415409. The reversal of 81415400 is 451418.

It is an interprime number because it is at equal distance from previous prime (81415391) and next prime (81415409).

It is a Harshad number since it is a multiple of its sum of digits (23).

It is not an unprimeable number, because it can be changed into a prime (81415409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 49796 + ... + 51404.

It is an arithmetic number, because the mean of its divisors is an integer number (2245950).

Almost surely, 2^81415400 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 81415400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107805600).

81415400 is an abundant number, since it is smaller than the sum of its proper divisors (134195800).

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

81415400 is a wasteful number, since it uses less digits than its factorization.

81415400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1659 (or 1650 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 81415400 is about 9023.0482654145. The cubic root of 81415400 is about 433.4132528467.

Adding to 81415400 its reverse (451418), we get a palindrome (81866818).

The spelling of 81415400 in words is "eighty-one million, four hundred fifteen thousand, four hundred".