21853261 has 4 divisors (see below), whose sum is σ = 22318272. Its totient is φ = 21388252.

The previous prime is 21853231. The next prime is 21853309. The reversal of 21853261 is 16235812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21853261 - 2⁵ = 21853229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21853231) 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 3 ways as a sum of consecutive naturals, for example, 232435 + ... + 232528.

It is an arithmetic number, because the mean of its divisors is an integer number (5579568).

Almost surely, 2^21853261 is an apocalyptic number.

It is an amenable number.

21853261 is a deficient number, since it is larger than the sum of its proper divisors (465011).

21853261 is an equidigital number, since it uses as much as digits as its factorization.

21853261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465010.

The product of its digits is 2880, while the sum is 28.

The square root of 21853261 is about 4674.7471589381. The cubic root of 21853261 is about 279.5795603228.

The spelling of 21853261 in words is "twenty-one million, eight hundred fifty-three thousand, two hundred sixty-one".