21523400 has 48 divisors (see below), whose sum is σ = 52228800. Its totient is φ = 8233280.

The previous prime is 21523399. The next prime is 21523417. The reversal of 21523400 is 432512.

It is a plaindrome in base 3 and base 9.

It is a zygodrome in base 3 and base 9.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2261 + ... + 6939.

It is an arithmetic number, because the mean of its divisors is an integer number (1088100).

Almost surely, 2^21523400 is an apocalyptic number.

21523400 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 21523400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26114400).

21523400 is an abundant number, since it is smaller than the sum of its proper divisors (30705400).

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

21523400 is a wasteful number, since it uses less digits than its factorization.

21523400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4718 (or 4709 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21523400 is about 4639.3318484454. The cubic root of 21523400 is about 278.1657311049.

Adding to 21523400 its reverse (432512), we get a palindrome (21955912).

The spelling of 21523400 in words is "twenty-one million, five hundred twenty-three thousand, four hundred".