21534400 has 84 divisors (see below), whose sum is σ = 54393592. Its totient is φ = 8386560.

The previous prime is 21534397. The next prime is 21534421. The reversal of 21534400 is 443512.

21534400 = 345² + 346² + ... + 472².

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, 68644 + ... + 68956.

Almost surely, 2^21534400 is an apocalyptic number.

21534400 is a gapful number since it is divisible by the number (20) 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 21534400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27196796).

21534400 is an abundant number, since it is smaller than the sum of its proper divisors (32859192).

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

21534400 is a wasteful number, since it uses less digits than its factorization.

21534400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21534400 is about 4640.5172125529. The cubic root of 21534400 is about 278.2131105761.

Adding to 21534400 its reverse (443512), we get a palindrome (21977912).

The spelling of 21534400 in words is "twenty-one million, five hundred thirty-four thousand, four hundred".