21855149 has 16 divisors (see below), whose sum is σ = 24727680. Its totient is φ = 19192320.

The previous prime is 21855143. The next prime is 21855157. The reversal of 21855149 is 94155812.

It is not a de Polignac number, because 21855149 - 2¹⁶ = 21789613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855143) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22457 + ... + 23409.

It is an arithmetic number, because the mean of its divisors is an integer number (1545480).

Almost surely, 2^21855149 is an apocalyptic number.

It is an amenable number.

21855149 is a deficient number, since it is larger than the sum of its proper divisors (2872531).

21855149 is a wasteful number, since it uses less digits than its factorization.

21855149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060.

The product of its digits is 14400, while the sum is 35.

The square root of 21855149 is about 4674.9490906319. The cubic root of 21855149 is about 279.5876114631.

The spelling of 21855149 in words is "twenty-one million, eight hundred fifty-five thousand, one hundred forty-nine".