21305214 has 64 divisors (see below), whose sum is σ = 54604800. Its totient is φ = 6031584.

The previous prime is 21305209. The next prime is 21305231. The reversal of 21305214 is 41250312.

It is a super-3 number, since 3×21305214³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 59167 + ... + 59525.

It is an arithmetic number, because the mean of its divisors is an integer number (853200).

Almost surely, 2^21305214 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21305214, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27302400).

21305214 is an abundant number, since it is smaller than the sum of its proper divisors (33299586).

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

21305214 is a wasteful number, since it uses less digits than its factorization.

21305214 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534 (or 528 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21305214 is about 4615.7571426582. The cubic root of 21305214 is about 277.2226008071. Note that the first 3 decimals are identical.

Adding to 21305214 its reverse (41250312), we get a palindrome (62555526).

The spelling of 21305214 in words is "twenty-one million, three hundred five thousand, two hundred fourteen".