21440136 has 16 divisors (see below), whose sum is σ = 53600400. Its totient is φ = 7146704.

The previous prime is 21440129. The next prime is 21440137. The reversal of 21440136 is 63104412.

It is not an unprimeable number, because it can be changed into a prime (21440137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 446646 + ... + 446693.

It is an arithmetic number, because the mean of its divisors is an integer number (3350025).

Almost surely, 2^21440136 is an apocalyptic number.

It is an amenable number.

21440136 is an abundant number, since it is smaller than the sum of its proper divisors (32160264).

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

21440136 is a wasteful number, since it uses less digits than its factorization.

21440136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 893348 (or 893344 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21440136 is about 4630.3494468560. The cubic root of 21440136 is about 277.8065697208.

Adding to 21440136 its reverse (63104412), we get a palindrome (84544548).

The spelling of 21440136 in words is "twenty-one million, four hundred forty thousand, one hundred thirty-six".