21736242 has 128 divisors (see below), whose sum is σ = 57784320. Its totient is φ = 5987520.

The previous prime is 21736237. The next prime is 21736259. The reversal of 21736242 is 24263712.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 505473 + ... + 505515.

It is an arithmetic number, because the mean of its divisors is an integer number (451440).

Almost surely, 2^21736242 is an apocalyptic number.

21736242 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21736242, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28892160).

21736242 is an abundant number, since it is smaller than the sum of its proper divisors (36048078).

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

21736242 is a wasteful number, since it uses less digits than its factorization.

21736242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 119 counting only the distinct ones).

The product of its digits is 4032, while the sum is 27.

The square root of 21736242 is about 4662.2142807898. The cubic root of 21736242 is about 279.0796396537.

Adding to 21736242 its reverse (24263712), we get a palindrome (45999954).

The spelling of 21736242 in words is "twenty-one million, seven hundred thirty-six thousand, two hundred forty-two".