21853481 has 16 divisors (see below), whose sum is σ = 24503808. Its totient is φ = 19353600.

The previous prime is 21853399. The next prime is 21853487. The reversal of 21853481 is 18435812.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21853481 is a prime.

It is a super-2 number, since 2×21853481² = 955149263634722, which contains 22 as substring.

It is a Duffinian number.

Its product of digits (7680) is a multiple of the sum of its prime divisors (512).

It is not an unprimeable number, because it can be changed into a prime (21853487) 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 15 ways as a sum of consecutive naturals, for example, 84905 + ... + 85161.

It is an arithmetic number, because the mean of its divisors is an integer number (1531488).

Almost surely, 2^21853481 is an apocalyptic number.

It is an amenable number.

21853481 is a deficient number, since it is larger than the sum of its proper divisors (2650327).

21853481 is a wasteful number, since it uses less digits than its factorization.

21853481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512.

The product of its digits is 7680, while the sum is 32.

The square root of 21853481 is about 4674.7706895633. The cubic root of 21853481 is about 279.5804985092.

The spelling of 21853481 in words is "twenty-one million, eight hundred fifty-three thousand, four hundred eighty-one".