21187296 has 72 divisors (see below), whose sum is σ = 64897560. Its totient is φ = 6518016.

The previous prime is 21187279. The next prime is 21187303. The reversal of 21187296 is 69278112.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21187296.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 915 + ... + 6573.

It is an arithmetic number, because the mean of its divisors is an integer number (901355).

Almost surely, 2^21187296 is an apocalyptic number.

21187296 is a gapful number since it is divisible by the number (26) 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 21187296, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32448780).

21187296 is an abundant number, since it is smaller than the sum of its proper divisors (43710264).

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

21187296 is a wasteful number, since it uses less digits than its factorization.

21187296 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5688 (or 5677 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21187296 is about 4602.9660003089. The cubic root of 21187296 is about 276.7102062088.

The spelling of 21187296 in words is "twenty-one million, one hundred eighty-seven thousand, two hundred ninety-six".