21440536 has 64 divisors (see below), whose sum is σ = 46781280. Its totient is φ = 9123840.

The previous prime is 21440527. The next prime is 21440537. The reversal of 21440536 is 63504412.

It is a self number, because there is not a number n which added to its sum of digits gives 21440536.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 118366 + ... + 118546.

Almost surely, 2^21440536 is an apocalyptic number.

21440536 is a gapful number since it is divisible by the number (26) 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 21440536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23390640).

21440536 is an abundant number, since it is smaller than the sum of its proper divisors (25340744).

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

21440536 is a wasteful number, since it uses less digits than its factorization.

21440536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21440536 is about 4630.3926399389. The cubic root of 21440536 is about 277.8082973519.

Adding to 21440536 its reverse (63504412), we get a palindrome (84944948).

The spelling of 21440536 in words is "twenty-one million, four hundred forty thousand, five hundred thirty-six".