21447860 has 48 divisors (see below), whose sum is σ = 51770880. Its totient is φ = 7311360.

The previous prime is 21447859. The next prime is 21447869. The reversal of 21447860 is 6874412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21447869) by changing a digit.

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, 33140 + ... + 33780.

It is an arithmetic number, because the mean of its divisors is an integer number (1078560).

Almost surely, 2^21447860 is an apocalyptic number.

21447860 is a gapful number since it is divisible by the number (20) 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 21447860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25885440).

21447860 is an abundant number, since it is smaller than the sum of its proper divisors (30323020).

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

21447860 is a wasteful number, since it uses less digits than its factorization.

21447860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 896 (or 894 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21447860 is about 4631.1834340695. The cubic root of 21447860 is about 277.8399264793.

The spelling of 21447860 in words is "twenty-one million, four hundred forty-seven thousand, eight hundred sixty".