21035644 has 12 divisors (see below), whose sum is σ = 42071344. Its totient is φ = 9015264.

The previous prime is 21035633. The next prime is 21035687. The reversal of 21035644 is 44653012.

21035644 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375609 + ... + 375664.

Almost surely, 2^21035644 is an apocalyptic number.

It is an amenable number.

21035644 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21035644 is a wasteful number, since it uses less digits than its factorization.

21035644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 751284 (or 751282 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21035644 is about 4586.4631253287. The cubic root of 21035644 is about 276.0484232058.

Adding to 21035644 its reverse (44653012), we get a palindrome (65688656).

The spelling of 21035644 in words is "twenty-one million, thirty-five thousand, six hundred forty-four".