21554421 has 8 divisors (see below), whose sum is σ = 32844864. Its totient is φ = 12316800.

The previous prime is 21554383. The next prime is 21554443. The reversal of 21554421 is 12445512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21554421 - 2¹¹ = 21552373 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21554391 and 21554400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 513180 + ... + 513221.

It is an arithmetic number, because the mean of its divisors is an integer number (4105608).

Almost surely, 2^21554421 is an apocalyptic number.

21554421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21554421 is a deficient number, since it is larger than the sum of its proper divisors (11290443).

21554421 is a wasteful number, since it uses less digits than its factorization.

21554421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1026411.

The product of its digits is 1600, while the sum is 24.

The square root of 21554421 is about 4642.6739062743. The cubic root of 21554421 is about 278.2993041293.

Adding to 21554421 its reverse (12445512), we get a palindrome (33999933).

The spelling of 21554421 in words is "twenty-one million, five hundred fifty-four thousand, four hundred twenty-one".