21544245 has 32 divisors (see below), whose sum is σ = 39628800. Its totient is φ = 11092032.

The previous prime is 21544231. The next prime is 21544273. The reversal of 21544245 is 54244512.

21544245 is a `hidden beast` number, since 215 + 442 + 4 + 5 = 666.

It is not a de Polignac number, because 21544245 - 2⁵ = 21544213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 31 ways as a sum of consecutive naturals, for example, 1164 + ... + 6666.

It is an arithmetic number, because the mean of its divisors is an integer number (1238400).

Almost surely, 2^21544245 is an apocalyptic number.

It is an amenable number.

21544245 is a deficient number, since it is larger than the sum of its proper divisors (18084555).

21544245 is a wasteful number, since it uses less digits than its factorization.

21544245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5546 (or 5540 counting only the distinct ones).

The product of its digits is 6400, while the sum is 27.

The square root of 21544245 is about 4641.5778567207. The cubic root of 21544245 is about 278.2555015223.

Adding to 21544245 its reverse (54244512), we get a palindrome (75788757).

The spelling of 21544245 in words is "twenty-one million, five hundred forty-four thousand, two hundred forty-five".