21853451 has 4 divisors (see below), whose sum is σ = 22386504. Its totient is φ = 21320400.

The previous prime is 21853399. The next prime is 21853487. The reversal of 21853451 is 15435812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21853451 - 2⁶ = 21853387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21853751) 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, 266465 + ... + 266546.

It is an arithmetic number, because the mean of its divisors is an integer number (5596626).

Almost surely, 2^21853451 is an apocalyptic number.

21853451 is a deficient number, since it is larger than the sum of its proper divisors (533053).

21853451 is an equidigital number, since it uses as much as digits as its factorization.

21853451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533052.

The product of its digits is 4800, while the sum is 29.

The square root of 21853451 is about 4674.7674808486. The cubic root of 21853451 is about 279.5803705751.

The spelling of 21853451 in words is "twenty-one million, eight hundred fifty-three thousand, four hundred fifty-one".