21355249 has 8 divisors (see below), whose sum is σ = 22514688. Its totient is φ = 20225280.

The previous prime is 21355241. The next prime is 21355261. The reversal of 21355249 is 94255312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21355249 - 2³ = 21355241 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21355249.

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 in 7 ways as a sum of consecutive naturals, for example, 5872 + ... + 8785.

It is an arithmetic number, because the mean of its divisors is an integer number (2814336).

Almost surely, 2^21355249 is an apocalyptic number.

It is an amenable number.

21355249 is a deficient number, since it is larger than the sum of its proper divisors (1159439).

21355249 is a wasteful number, since it uses less digits than its factorization.

21355249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14735.

The product of its digits is 10800, while the sum is 31.

The square root of 21355249 is about 4621.1739850389. The cubic root of 21355249 is about 277.4394489535.

The spelling of 21355249 in words is "twenty-one million, three hundred fifty-five thousand, two hundred forty-nine".