21249144 has 144 divisors (see below), whose sum is σ = 70691400. Its totient is φ = 5733504.

The previous prime is 21249143. The next prime is 21249149. The reversal of 21249144 is 44194212.

It is a happy number.

It is a super-3 number, since 3×21249144³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21249143) 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 35 ways as a sum of consecutive naturals, for example, 66874 + ... + 67190.

Almost surely, 2^21249144 is an apocalyptic number.

21249144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21249144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35345700).

21249144 is an abundant number, since it is smaller than the sum of its proper divisors (49442256).

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

21249144 is a wasteful number, since it uses less digits than its factorization.

21249144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362 (or 348 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21249144 is about 4609.6793814755. The cubic root of 21249144 is about 276.9791936133.

The spelling of 21249144 in words is "twenty-one million, two hundred forty-nine thousand, one hundred forty-four".