21383509 has 8 divisors (see below), whose sum is σ = 25034688. Its totient is φ = 17881440.

The previous prime is 21383503. The next prime is 21383573. The reversal of 21383509 is 90538312.

It is a happy number.

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 21383509 - 2⁷ = 21383381 is a prime.

It is a super-3 number, since 3×21383509³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21383503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36967 + ... + 37540.

It is an arithmetic number, because the mean of its divisors is an integer number (3129336).

Almost surely, 2^21383509 is an apocalyptic number.

It is an amenable number.

21383509 is a deficient number, since it is larger than the sum of its proper divisors (3651179).

21383509 is an equidigital number, since it uses as much as digits as its factorization.

21383509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74555.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 21383509 is about 4624.2306387117. The cubic root of 21383509 is about 277.5617761446.

The spelling of 21383509 in words is "twenty-one million, three hundred eighty-three thousand, five hundred nine".