21553366 has 4 divisors (see below), whose sum is σ = 32330052. Its totient is φ = 10776682.

The previous prime is 21553361. The next prime is 21553379. The reversal of 21553366 is 66335512.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5388340 + ... + 5388343.

It is an arithmetic number, because the mean of its divisors is an integer number (8082513).

Almost surely, 2^21553366 is an apocalyptic number.

21553366 is a deficient number, since it is larger than the sum of its proper divisors (10776686).

21553366 is a wasteful number, since it uses less digits than its factorization.

21553366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10776685.

The product of its digits is 16200, while the sum is 31.

The square root of 21553366 is about 4642.5602850152. The cubic root of 21553366 is about 278.2947635209.

Adding to 21553366 its reverse (66335512), we get a palindrome (87888878).

The spelling of 21553366 in words is "twenty-one million, five hundred fifty-three thousand, three hundred sixty-six".