21355244 has 6 divisors (see below), whose sum is σ = 37371684. Its totient is φ = 10677620.

The previous prime is 21355241. The next prime is 21355261. The reversal of 21355244 is 44255312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21355241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2669402 + ... + 2669409.

It is an arithmetic number, because the mean of its divisors is an integer number (6228614).

Almost surely, 2^21355244 is an apocalyptic number.

It is an amenable number.

21355244 is a deficient number, since it is larger than the sum of its proper divisors (16016440).

21355244 is a wasteful number, since it uses less digits than its factorization.

21355244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5338815 (or 5338813 counting only the distinct ones).

The product of its digits is 4800, while the sum is 26.

The square root of 21355244 is about 4621.1734440508. The cubic root of 21355244 is about 277.4394273008.

The spelling of 21355244 in words is "twenty-one million, three hundred fifty-five thousand, two hundred forty-four".