21431383 has 2 divisors, whose sum is σ = 21431384. Its totient is φ = 21431382.

The previous prime is 21431359. The next prime is 21431387. The reversal of 21431383 is 38313412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21431383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21431387) 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, 10715691 + 10715692.

It is an arithmetic number, because the mean of its divisors is an integer number (10715692).

Almost surely, 2^21431383 is an apocalyptic number.

21431383 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431383 is an equidigital number, since it uses as much as digits as its factorization.

21431383 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 25.

The square root of 21431383 is about 4629.4041733251. The cubic root of 21431383 is about 277.7687594524.

Adding to 21431383 its reverse (38313412), we get a palindrome (59744795).

The spelling of 21431383 in words is "twenty-one million, four hundred thirty-one thousand, three hundred eighty-three".