21099472 has 40 divisors (see below), whose sum is σ = 43468200. Its totient is φ = 9902592.

The previous prime is 21099469. The next prime is 21099503. The reversal of 21099472 is 27499012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14318656 + 6780816 = 3784^2 + 2604^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16554 + ... + 17782.

It is an arithmetic number, because the mean of its divisors is an integer number (1086705).

Almost surely, 2^21099472 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 21099472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21734100).

21099472 is an abundant number, since it is smaller than the sum of its proper divisors (22368728).

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

21099472 is a wasteful number, since it uses less digits than its factorization.

21099472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1303 (or 1297 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21099472 is about 4593.4161579374. The cubic root of 21099472 is about 276.3273438765.

The spelling of 21099472 in words is "twenty-one million, ninety-nine thousand, four hundred seventy-two".