21554320 has 20 divisors (see below), whose sum is σ = 50113980. Its totient is φ = 8621696.

The previous prime is 21554311. The next prime is 21554359. The reversal of 21554320 is 2345512.

It can be written as a sum of positive squares in 2 ways, for example, as 4875264 + 16679056 = 2208^2 + 4084^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 21554291 and 21554300.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134635 + ... + 134794.

It is an arithmetic number, because the mean of its divisors is an integer number (2505699).

Almost surely, 2^21554320 is an apocalyptic number.

21554320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21554320 is an abundant number, since it is smaller than the sum of its proper divisors (28559660).

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

21554320 is a wasteful number, since it uses less digits than its factorization.

21554320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269442 (or 269436 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21554320 is about 4642.6630289092. The cubic root of 21554320 is about 278.2988694424.

Adding to 21554320 its reverse (2345512), we get a palindrome (23899832).

The spelling of 21554320 in words is "twenty-one million, five hundred fifty-four thousand, three hundred twenty".