21213433 has 8 divisors (see below), whose sum is σ = 22594248. Its totient is φ = 19847424.

The previous prime is 21213431. The next prime is 21213449. The reversal of 21213433 is 33431212.

It can be written as a sum of positive squares in 4 ways, for example, as 14227984 + 6985449 = 3772^2 + 2643^2 .

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 21213433 - 2¹ = 21213431 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21213433.

It is not an unprimeable number, because it can be changed into a prime (21213431) 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 7 ways as a sum of consecutive naturals, for example, 666 + ... + 6547.

It is an arithmetic number, because the mean of its divisors is an integer number (2824281).

Almost surely, 2^21213433 is an apocalyptic number.

It is an amenable number.

21213433 is a deficient number, since it is larger than the sum of its proper divisors (1380815).

21213433 is a wasteful number, since it uses less digits than its factorization.

21213433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7403.

The product of its digits is 432, while the sum is 19.

The square root of 21213433 is about 4605.8042728714. The cubic root of 21213433 is about 276.8239442196.

Adding to 21213433 its reverse (33431212), we get a palindrome (54644645).

The spelling of 21213433 in words is "twenty-one million, two hundred thirteen thousand, four hundred thirty-three".