21331351 has 4 divisors (see below), whose sum is σ = 21907912. Its totient is φ = 20754792.

The previous prime is 21331339. The next prime is 21331361. The reversal of 21331351 is 15313312.

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 21331351 - 2⁹ = 21330839 is a prime.

It is a super-3 number, since 3×21331351³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288225 + ... + 288298.

It is an arithmetic number, because the mean of its divisors is an integer number (5476978).

Almost surely, 2^21331351 is an apocalyptic number.

21331351 is a deficient number, since it is larger than the sum of its proper divisors (576561).

21331351 is an equidigital number, since it uses as much as digits as its factorization.

21331351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576560.

The product of its digits is 270, while the sum is 19.

The square root of 21331351 is about 4618.5875546535. The cubic root of 21331351 is about 277.3359190169.

Adding to 21331351 its reverse (15313312), we get a palindrome (36644663).

The spelling of 21331351 in words is "twenty-one million, three hundred thirty-one thousand, three hundred fifty-one".