21749644 has 24 divisors (see below), whose sum is σ = 43598240. Its totient is φ = 9300096.

The previous prime is 21749621. The next prime is 21749657. The reversal of 21749644 is 44694712.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22744 + ... + 23680.

Almost surely, 2^21749644 is an apocalyptic number.

It is an amenable number.

21749644 is an abundant number, since it is smaller than the sum of its proper divisors (21848596).

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

21749644 is a wasteful number, since it uses less digits than its factorization.

21749644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1777 (or 1775 counting only the distinct ones).

The product of its digits is 48384, while the sum is 37.

The square root of 21749644 is about 4663.6513591820. The cubic root of 21749644 is about 279.1369856120.

The spelling of 21749644 in words is "twenty-one million, seven hundred forty-nine thousand, six hundred forty-four".