21229392 has 80 divisors (see below), whose sum is σ = 57674880. Its totient is φ = 6720000.

The previous prime is 21229387. The next prime is 21229399. The reversal of 21229392 is 29392212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21229399) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 140517 + ... + 140667.

It is an arithmetic number, because the mean of its divisors is an integer number (720936).

Almost surely, 2^21229392 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 21229392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28837440).

21229392 is an abundant number, since it is smaller than the sum of its proper divisors (36445488).

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

21229392 is a wasteful number, since it uses less digits than its factorization.

21229392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 286 counting only the distinct ones).

The product of its digits is 3888, while the sum is 30.

The square root of 21229392 is about 4607.5364350160. The cubic root of 21229392 is about 276.8933456210.

Subtracting 21229392 from its reverse (29392212), we obtain a triangular number (8162820 = T₄₀₄₀).

The spelling of 21229392 in words is "twenty-one million, two hundred twenty-nine thousand, three hundred ninety-two".