21533131 has 2 divisors, whose sum is σ = 21533132. Its totient is φ = 21533130.

The previous prime is 21533123. The next prime is 21533143. The reversal of 21533131 is 13133512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21533131 - 2³ = 21533123 is a prime.

It is a super-2 number, since 2×21533131² = 927351461326322, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21533099 and 21533108.

It is not a weakly prime, because it can be changed into another prime (21533111) 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 as a sum of consecutive naturals, namely, 10766565 + 10766566.

It is an arithmetic number, because the mean of its divisors is an integer number (10766566).

Almost surely, 2^21533131 is an apocalyptic number.

21533131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21533131 is an equidigital number, since it uses as much as digits as its factorization.

21533131 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21533131 is about 4640.3804800900. The cubic root of 21533131 is about 278.2076455314.

Adding to 21533131 its reverse (13133512), we get a palindrome (34666643).

The spelling of 21533131 in words is "twenty-one million, five hundred thirty-three thousand, one hundred thirty-one".