21704136 has 64 divisors (see below), whose sum is σ = 56142720. Its totient is φ = 6988800.

The previous prime is 21704131. The next prime is 21704143. The reversal of 21704136 is 63140712.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21704131) 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, 143661 + ... + 143811.

It is an arithmetic number, because the mean of its divisors is an integer number (877230).

Almost surely, 2^21704136 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 21704136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28071360).

21704136 is an abundant number, since it is smaller than the sum of its proper divisors (34438584).

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

21704136 is a wasteful number, since it uses less digits than its factorization.

21704136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326 (or 322 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21704136 is about 4658.7697946990. The cubic root of 21704136 is about 278.9421650138.

Adding to 21704136 its reverse (63140712), we get a palindrome (84844848).

The spelling of 21704136 in words is "twenty-one million, seven hundred four thousand, one hundred thirty-six".