21743636 has 6 divisors (see below), whose sum is σ = 38051370. Its totient is φ = 10871816.

The previous prime is 21743627. The next prime is 21743639. The reversal of 21743636 is 63634712.

It can be written as a sum of positive squares in only one way, i.e., 15523600 + 6220036 = 3940^2 + 2494^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21743639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2717951 + ... + 2717958.

It is an arithmetic number, because the mean of its divisors is an integer number (6341895).

Almost surely, 2^21743636 is an apocalyptic number.

It is an amenable number.

21743636 is a deficient number, since it is larger than the sum of its proper divisors (16307734).

21743636 is a wasteful number, since it uses less digits than its factorization.

21743636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5435913 (or 5435911 counting only the distinct ones).

The product of its digits is 18144, while the sum is 32.

The square root of 21743636 is about 4663.0071842106. The cubic root of 21743636 is about 279.1112808319. Note that the first 3 decimals are identical.

The spelling of 21743636 in words is "twenty-one million, seven hundred forty-three thousand, six hundred thirty-six".