21642936 has 64 divisors (see below), whose sum is σ = 63175680. Its totient is φ = 6049920.

The previous prime is 21642923. The next prime is 21642937. The reversal of 21642936 is 63924612.

It is a junction number, because it is equal to n+sod(n) for n = 21642897 and 21642906.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642937) 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, 6526 + ... + 9266.

It is an arithmetic number, because the mean of its divisors is an integer number (987120).

Almost surely, 2^21642936 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 21642936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31587840).

21642936 is an abundant number, since it is smaller than the sum of its proper divisors (41532744).

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

21642936 is a wasteful number, since it uses less digits than its factorization.

21642936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2804 (or 2800 counting only the distinct ones).

The product of its digits is 15552, while the sum is 33.

The square root of 21642936 is about 4652.1969003902. The cubic root of 21642936 is about 278.6797368268.

It can be divided in two parts, 21642 and 936, that added together give a triangular number (22578 = T₂₁₂).

The spelling of 21642936 in words is "twenty-one million, six hundred forty-two thousand, nine hundred thirty-six".