21440216 has 16 divisors (see below), whose sum is σ = 45943440. Its totient is φ = 9188640.

The previous prime is 21440207. The next prime is 21440233. The reversal of 21440216 is 61204412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 191375 + ... + 191486.

It is an arithmetic number, because the mean of its divisors is an integer number (2871465).

Almost surely, 2^21440216 is an apocalyptic number.

It is an amenable number.

21440216 is an abundant number, since it is smaller than the sum of its proper divisors (24503224).

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

21440216 is a wasteful number, since it uses less digits than its factorization.

21440216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382874 (or 382870 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21440216 is about 4630.3580855048. The cubic root of 21440216 is about 277.8069152487.

Adding to 21440216 its reverse (61204412), we get a palindrome (82644628).

The spelling of 21440216 in words is "twenty-one million, four hundred forty thousand, two hundred sixteen".