21383553 has 8 divisors (see below), whose sum is σ = 28805728. Its totient is φ = 14108544.

The previous prime is 21383503. The next prime is 21383573. The reversal of 21383553 is 35538312.

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

It is not a de Polignac number, because 21383553 - 2¹⁴ = 21367169 is a prime.

It is a super-3 number, since 3×21383553³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21383553.

It is not an unprimeable number, because it can be changed into a prime (21383503) 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, 36451 + ... + 37032.

It is an arithmetic number, because the mean of its divisors is an integer number (3600716).

Almost surely, 2^21383553 is an apocalyptic number.

It is an amenable number.

21383553 is a deficient number, since it is larger than the sum of its proper divisors (7422175).

21383553 is an equidigital number, since it uses as much as digits as its factorization.

21383553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73583.

The product of its digits is 10800, while the sum is 30.

The square root of 21383553 is about 4624.2353962574. The cubic root of 21383553 is about 277.5619665204.

The spelling of 21383553 in words is "twenty-one million, three hundred eighty-three thousand, five hundred fifty-three".