21553889 has 8 divisors (see below), whose sum is σ = 24758400. Its totient is φ = 18380736.

The previous prime is 21553867. The next prime is 21553901. The reversal of 21553889 is 98835512.

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

It is a cyclic number.

It is not a de Polignac number, because 21553889 - 2⁸ = 21553633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21553859) 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 in 7 ways as a sum of consecutive naturals, for example, 6344 + ... + 9129.

It is an arithmetic number, because the mean of its divisors is an integer number (3094800).

Almost surely, 2^21553889 is an apocalyptic number.

It is an amenable number.

21553889 is a deficient number, since it is larger than the sum of its proper divisors (3204511).

21553889 is a wasteful number, since it uses less digits than its factorization.

21553889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15679.

The product of its digits is 86400, while the sum is 41.

The square root of 21553889 is about 4642.6166113518. The cubic root of 21553889 is about 278.2970144761.

The spelling of 21553889 in words is "twenty-one million, five hundred fifty-three thousand, eight hundred eighty-nine".