21425644 has 12 divisors (see below), whose sum is σ = 39700584. Its totient is φ = 10082624.

The previous prime is 21425641. The next prime is 21425659. The reversal of 21425644 is 44652412.

It is not an unprimeable number, because it can be changed into a prime (21425641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157474 + ... + 157609.

It is an arithmetic number, because the mean of its divisors is an integer number (3308382).

Almost surely, 2^21425644 is an apocalyptic number.

It is an amenable number.

21425644 is a deficient number, since it is larger than the sum of its proper divisors (18274940).

21425644 is a wasteful number, since it uses less digits than its factorization.

21425644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315104 (or 315102 counting only the distinct ones).

The product of its digits is 7680, while the sum is 28.

The square root of 21425644 is about 4628.7842896380. The cubic root of 21425644 is about 277.7439631490.

The spelling of 21425644 in words is "twenty-one million, four hundred twenty-five thousand, six hundred forty-four".