21641236 has 6 divisors (see below), whose sum is σ = 37872170. Its totient is φ = 10820616.

The previous prime is 21641231. The next prime is 21641239. The reversal of 21641236 is 63214612.

It can be written as a sum of positive squares in only one way, i.e., 19802500 + 1838736 = 4450^2 + 1356^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21641236.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2705151 + ... + 2705158.

Almost surely, 2^21641236 is an apocalyptic number.

It is an amenable number.

21641236 is a deficient number, since it is larger than the sum of its proper divisors (16230934).

21641236 is a wasteful number, since it uses less digits than its factorization.

21641236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5410313 (or 5410311 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21641236 is about 4652.0141874246. The cubic root of 21641236 is about 278.6724400972.

Adding to 21641236 its reverse (63214612), we get a palindrome (84855848).

The spelling of 21641236 in words is "twenty-one million, six hundred forty-one thousand, two hundred thirty-six".