21855549 has 8 divisors (see below), whose sum is σ = 29205792. Its totient is φ = 14537840.

The previous prime is 21855541. The next prime is 21855553. The reversal of 21855549 is 94555812.

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 21855549 - 2³ = 21855541 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6519 + ... + 9284.

It is an arithmetic number, because the mean of its divisors is an integer number (3650724).

Almost surely, 2^21855549 is an apocalyptic number.

It is an amenable number.

21855549 is a deficient number, since it is larger than the sum of its proper divisors (7350243).

21855549 is a wasteful number, since it uses less digits than its factorization.

21855549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16267.

The product of its digits is 72000, while the sum is 39.

The square root of 21855549 is about 4674.9918716507. The cubic root of 21855549 is about 279.5893171536.

The spelling of 21855549 in words is "twenty-one million, eight hundred fifty-five thousand, five hundred forty-nine".