21554105 has 24 divisors (see below), whose sum is σ = 28070280. Its totient is φ = 15868160.

The previous prime is 21554081. The next prime is 21554111. The reversal of 21554105 is 50145512.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3644281 + 17909824 = 1909^2 + 4232^2 .

It is not a de Polignac number, because 21554105 - 2⁶ = 21554041 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 76565 + ... + 76845.

It is an arithmetic number, because the mean of its divisors is an integer number (1169595).

Almost surely, 2^21554105 is an apocalyptic number.

It is an amenable number.

21554105 is a deficient number, since it is larger than the sum of its proper divisors (6516175).

21554105 is a wasteful number, since it uses less digits than its factorization.

21554105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 21554105 is about 4642.6398740372. The cubic root of 21554105 is about 278.2979441143.

Adding to 21554105 its reverse (50145512), we get a palindrome (71699617).

The spelling of 21554105 in words is "twenty-one million, five hundred fifty-four thousand, one hundred five".