21355444 has 12 divisors (see below), whose sum is σ = 40769568. Its totient is φ = 9707000.

The previous prime is 21355409. The next prime is 21355447. The reversal of 21355444 is 44455312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355447) 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, 242632 + ... + 242719.

It is an arithmetic number, because the mean of its divisors is an integer number (3397464).

Almost surely, 2^21355444 is an apocalyptic number.

It is an amenable number.

21355444 is a deficient number, since it is larger than the sum of its proper divisors (19414124).

21355444 is a wasteful number, since it uses less digits than its factorization.

21355444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485366 (or 485364 counting only the distinct ones).

The product of its digits is 9600, while the sum is 28.

The square root of 21355444 is about 4621.1950835255. The cubic root of 21355444 is about 277.4402934067.

The spelling of 21355444 in words is "twenty-one million, three hundred fifty-five thousand, four hundred forty-four".