21384331 has 4 divisors (see below), whose sum is σ = 21528000. Its totient is φ = 21240664.

The previous prime is 21384313. The next prime is 21384347. The reversal of 21384331 is 13348312.

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 21384331 - 2⁵ = 21384299 is a prime.

It is a super-2 number, since 2×21384331² = 914579224635122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21384296 and 21384305.

It is not an unprimeable number, because it can be changed into a prime (21384301) 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 3 ways as a sum of consecutive naturals, for example, 71611 + ... + 71908.

It is an arithmetic number, because the mean of its divisors is an integer number (5382000).

Almost surely, 2^21384331 is an apocalyptic number.

21384331 is a deficient number, since it is larger than the sum of its proper divisors (143669).

21384331 is a wasteful number, since it uses less digits than its factorization.

21384331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143668.

The product of its digits is 1728, while the sum is 25.

The square root of 21384331 is about 4624.3195175074. The cubic root of 21384331 is about 277.5653326681.

The spelling of 21384331 in words is "twenty-one million, three hundred eighty-four thousand, three hundred thirty-one".