21133431 has 48 divisors (see below), whose sum is σ = 36560160. Its totient is φ = 11612160.

The previous prime is 21133429. The next prime is 21133433. The reversal of 21133431 is 13433112.

It is an interprime number because it is at equal distance from previous prime (21133429) and next prime (21133433).

It is not a de Polignac number, because 21133431 - 2¹ = 21133429 is a prime.

It is a super-4 number, since 4×21133431⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133433) 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 47 ways as a sum of consecutive naturals, for example, 48591 + ... + 49023.

It is an arithmetic number, because the mean of its divisors is an integer number (761670).

Almost surely, 2^21133431 is an apocalyptic number.

21133431 is a deficient number, since it is larger than the sum of its proper divisors (15426729).

21133431 is a wasteful number, since it uses less digits than its factorization.

21133431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 496 (or 493 counting only the distinct ones).

The product of its digits is 216, while the sum is 18.

The square root of 21133431 is about 4597.1111581079. Note that the first 4 decimals coincide. The cubic root of 21133431 is about 276.4755114143.

Adding to 21133431 its reverse (13433112), we get a palindrome (34566543).

The spelling of 21133431 in words is "twenty-one million, one hundred thirty-three thousand, four hundred thirty-one".