21440364 has 48 divisors (see below), whose sum is σ = 55520640. Its totient is φ = 6384640.

The previous prime is 21440357. The next prime is 21440369. The reversal of 21440364 is 46304412.

It is not an unprimeable number, because it can be changed into a prime (21440369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6412 + ... + 9164.

It is an arithmetic number, because the mean of its divisors is an integer number (1156680).

Almost surely, 2^21440364 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 21440364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27760320).

21440364 is an abundant number, since it is smaller than the sum of its proper divisors (34080276).

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

21440364 is a wasteful number, since it uses less digits than its factorization.

21440364 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2830 (or 2828 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 21440364 is about 4630.3740669626. The cubic root of 21440364 is about 277.8075544731.

Adding to 21440364 its reverse (46304412), we get a palindrome (67744776).

The spelling of 21440364 in words is "twenty-one million, four hundred forty thousand, three hundred sixty-four".