21554400 has 144 divisors (see below), whose sum is σ = 80244864. Its totient is φ = 4922880.

The previous prime is 21554383. The next prime is 21554443. The reversal of 21554400 is 445512.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16159 + ... + 17441.

It is an arithmetic number, because the mean of its divisors is an integer number (557256).

Almost surely, 2^21554400 is an apocalyptic number.

21554400 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 21554400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40122432).

21554400 is an abundant number, since it is smaller than the sum of its proper divisors (58690464).

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

21554400 is a wasteful number, since it uses less digits than its factorization.

21554400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1313 (or 1300 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21554400 is about 4642.6716446460. The cubic root of 21554400 is about 278.2992137490.

Adding to 21554400 its reverse (445512), we get a palindrome (21999912).

It can be divided in two parts, 2155 and 4400, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 21554400 in words is "twenty-one million, five hundred fifty-four thousand, four hundred".