21431933 has 2 divisors, whose sum is σ = 21431934. Its totient is φ = 21431932.

The previous prime is 21431911. The next prime is 21431939. The reversal of 21431933 is 33913412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13935289 + 7496644 = 3733^2 + 2738^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431933 - 2¹⁰ = 21430909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21431939) 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 as a sum of consecutive naturals, namely, 10715966 + 10715967.

It is an arithmetic number, because the mean of its divisors is an integer number (10715967).

Almost surely, 2^21431933 is an apocalyptic number.

It is an amenable number.

21431933 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431933 is an equidigital number, since it uses as much as digits as its factorization.

21431933 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 26.

The square root of 21431933 is about 4629.4635758368. The cubic root of 21431933 is about 277.7711355864.

The spelling of 21431933 in words is "twenty-one million, four hundred thirty-one thousand, nine hundred thirty-three".