21849816 has 48 divisors (see below), whose sum is σ = 57135960. Its totient is φ = 6962560.

The previous prime is 21849809. The next prime is 21849857. The reversal of 21849816 is 61894812.

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 11 ways as a sum of consecutive naturals, for example, 11836 + ... + 13556.

Almost surely, 2^21849816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21849816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28567980).

21849816 is an abundant number, since it is smaller than the sum of its proper divisors (35286144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21849816 is a wasteful number, since it uses less digits than its factorization.

21849816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1776 (or 1749 counting only the distinct ones).

The product of its digits is 27648, while the sum is 39.

The square root of 21849816 is about 4674.3786752894. The cubic root of 21849816 is about 279.5648683553.

The spelling of 21849816 in words is "twenty-one million, eight hundred forty-nine thousand, eight hundred sixteen".