21887636 has 24 divisors (see below), whose sum is σ = 40942440. Its totient is φ = 10202112.

The previous prime is 21887633. The next prime is 21887641. The reversal of 21887636 is 63678812.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 11519236 + 10368400 = 3394^2 + 3220^2 .

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21887593 and 21887602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21887633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5936 + ... + 8888.

It is an arithmetic number, because the mean of its divisors is an integer number (1705935).

Almost surely, 2^21887636 is an apocalyptic number.

It is an amenable number.

21887636 is a deficient number, since it is larger than the sum of its proper divisors (19054804).

21887636 is a wasteful number, since it uses less digits than its factorization.

21887636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3083 (or 3081 counting only the distinct ones).

The product of its digits is 96768, while the sum is 41.

The square root of 21887636 is about 4678.4223836674. The cubic root of 21887636 is about 279.7260756443.

The spelling of 21887636 in words is "twenty-one million, eight hundred eighty-seven thousand, six hundred thirty-six".