21373243 has 2 divisors, whose sum is σ = 21373244. Its totient is φ = 21373242.

The previous prime is 21373237. The next prime is 21373249. The reversal of 21373243 is 34237312.

It is a balanced prime because it is at equal distance from previous prime (21373237) and next prime (21373249).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21373243 is a prime.

It is not a weakly prime, because it can be changed into another prime (21373249) 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, 10686621 + 10686622.

It is an arithmetic number, because the mean of its divisors is an integer number (10686622).

Almost surely, 2^21373243 is an apocalyptic number.

21373243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21373243 is an equidigital number, since it uses as much as digits as its factorization.

21373243 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 25.

The square root of 21373243 is about 4623.1204829639. The cubic root of 21373243 is about 277.5173508616.

The spelling of 21373243 in words is "twenty-one million, three hundred seventy-three thousand, two hundred forty-three".