81421400 has 48 divisors (see below), whose sum is σ = 189950640. Its totient is φ = 32457600.

The previous prime is 81421393. The next prime is 81421411. The reversal of 81421400 is 412418.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 83717 + ... + 84683.

It is an arithmetic number, because the mean of its divisors is an integer number (3957305).

Almost surely, 2^81421400 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 81421400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94975320).

81421400 is an abundant number, since it is smaller than the sum of its proper divisors (108529240).

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

81421400 is a wasteful number, since it uses less digits than its factorization.

81421400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1404 (or 1395 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 81421400 is about 9023.3807411635. The cubic root of 81421400 is about 433.4238995451.

Adding to 81421400 its reverse (412418), we get a palindrome (81833818).

The spelling of 81421400 in words is "eighty-one million, four hundred twenty-one thousand, four hundred".