21738736 has 40 divisors (see below), whose sum is σ = 45393920. Its totient is φ = 10051776.

The previous prime is 21738707. The next prime is 21738737. The reversal of 21738736 is 63783712.

It is a junction number, because it is equal to n+sod(n) for n = 21738695 and 21738704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21738737) 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 7 ways as a sum of consecutive naturals, for example, 12241 + ... + 13903.

It is an arithmetic number, because the mean of its divisors is an integer number (1134848).

Almost surely, 2^21738736 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 21738736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22696960).

21738736 is an abundant number, since it is smaller than the sum of its proper divisors (23655184).

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

21738736 is a wasteful number, since it uses less digits than its factorization.

21738736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1733 (or 1727 counting only the distinct ones).

The product of its digits is 42336, while the sum is 37.

The square root of 21738736 is about 4662.4817425916. The cubic root of 21738736 is about 279.0903130412.

The spelling of 21738736 in words is "twenty-one million, seven hundred thirty-eight thousand, seven hundred thirty-six".