21704436 has 60 divisors (see below), whose sum is σ = 61116132. Its totient is φ = 6676992.

The previous prime is 21704411. The next prime is 21704443. The reversal of 21704436 is 63440712.

21704436 is a `hidden beast` number, since 217 + 0 + 443 + 6 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8088336 + 13616100 = 2844^2 + 3690^2 .

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 polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1636 + ... + 6788.

Almost surely, 2^21704436 is an apocalyptic number.

21704436 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21704436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30558066).

21704436 is an abundant number, since it is smaller than the sum of its proper divisors (39411696).

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

21704436 is a wasteful number, since it uses less digits than its factorization.

21704436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5182 (or 5171 counting only the distinct ones).

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

The square root of 21704436 is about 4658.8019919288. The cubic root of 21704436 is about 278.9434502107.

The spelling of 21704436 in words is "twenty-one million, seven hundred four thousand, four hundred thirty-six".