21402216 has 96 divisors (see below), whose sum is σ = 64415520. Its totient is φ = 6364800.

The previous prime is 21402209. The next prime is 21402217. The reversal of 21402216 is 61220412.

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

It is not an unprimeable number, because it can be changed into a prime (21402217) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48091 + ... + 48533.

It is an arithmetic number, because the mean of its divisors is an integer number (670995).

Almost surely, 2^21402216 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 21402216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32207760).

21402216 is an abundant number, since it is smaller than the sum of its proper divisors (43013304).

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

21402216 is a wasteful number, since it uses less digits than its factorization.

21402216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527 (or 520 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21402216 is about 4626.2529113744. The cubic root of 21402216 is about 277.6426926230.

Adding to 21402216 its reverse (61220412), we get a palindrome (82622628).

It can be divided in two parts, 2140 and 2216, that added together give a square (4356 = 66²).

The spelling of 21402216 in words is "twenty-one million, four hundred two thousand, two hundred sixteen".