21171444 has 48 divisors (see below), whose sum is σ = 57028608. Its totient is φ = 5987808.

The previous prime is 21171407. The next prime is 21171461. The reversal of 21171444 is 44417112.

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

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 7429 + ... + 9875.

It is an arithmetic number, because the mean of its divisors is an integer number (1188096).

Almost surely, 2^21171444 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 21171444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28514304).

21171444 is an abundant number, since it is smaller than the sum of its proper divisors (35857164).

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

21171444 is a wasteful number, since it uses less digits than its factorization.

21171444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2564 (or 2562 counting only the distinct ones).

The product of its digits is 896, while the sum is 24.

The square root of 21171444 is about 4601.2437449020. The cubic root of 21171444 is about 276.6411789233.

Adding to 21171444 its reverse (44417112), we get a palindrome (65588556).

The spelling of 21171444 in words is "twenty-one million, one hundred seventy-one thousand, four hundred forty-four".