21447264 has 48 divisors (see below), whose sum is σ = 57682800. Its totient is φ = 6973440.

The previous prime is 21447259. The next prime is 21447277. The reversal of 21447264 is 46274412.

It is a tau number, because it is divible by the number of its divisors (48).

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, 1212 + ... + 6660.

It is an arithmetic number, because the mean of its divisors is an integer number (1201725).

Almost surely, 2^21447264 is an apocalyptic number.

21447264 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 21447264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28841400).

21447264 is an abundant number, since it is smaller than the sum of its proper divisors (36235536).

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

21447264 is a wasteful number, since it uses less digits than its factorization.

21447264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5503 (or 5495 counting only the distinct ones).

The product of its digits is 10752, while the sum is 30.

The square root of 21447264 is about 4631.1190872186. The cubic root of 21447264 is about 277.8373528872.

The spelling of 21447264 in words is "twenty-one million, four hundred forty-seven thousand, two hundred sixty-four".