21435644 has 24 divisors (see below), whose sum is σ = 38799600. Its totient is φ = 10356480.

The previous prime is 21435643. The next prime is 21435677. The reversal of 21435644 is 44653412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21435643) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 13652 + ... + 15140.

It is an arithmetic number, because the mean of its divisors is an integer number (1616650).

Almost surely, 2^21435644 is an apocalyptic number.

It is an amenable number.

21435644 is a deficient number, since it is larger than the sum of its proper divisors (17363956).

21435644 is a wasteful number, since it uses less digits than its factorization.

21435644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1613 (or 1611 counting only the distinct ones).

The product of its digits is 11520, while the sum is 29.

The square root of 21435644 is about 4629.8643608641. The cubic root of 21435644 is about 277.7871669478.

The spelling of 21435644 in words is "twenty-one million, four hundred thirty-five thousand, six hundred forty-four".