21033231 has 8 divisors (see below), whose sum is σ = 28111104. Its totient is φ = 13988760.

The previous prime is 21033223. The next prime is 21033239. The reversal of 21033231 is 13233012.

It is an interprime number because it is at equal distance from previous prime (21033223) and next prime (21033239).

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

It is not a de Polignac number, because 21033231 - 2³ = 21033223 is a prime.

It is a super-2 number, since 2×21033231² = 884793612598722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21033231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033239) 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, 6841 + ... + 9426.

It is an arithmetic number, because the mean of its divisors is an integer number (3513888).

Almost surely, 2^21033231 is an apocalyptic number.

21033231 is a deficient number, since it is larger than the sum of its proper divisors (7077873).

21033231 is a wasteful number, since it uses less digits than its factorization.

21033231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16701.

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 21033231 is about 4586.2000610527. The cubic root of 21033231 is about 276.0378676251.

Adding to 21033231 its reverse (13233012), we get a palindrome (34266243).

The spelling of 21033231 in words is "twenty-one million, thirty-three thousand, two hundred thirty-one".