21456373 has 2 divisors, whose sum is σ = 21456374. Its totient is φ = 21456372.

The previous prime is 21456349. The next prime is 21456403. The reversal of 21456373 is 37365412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14607684 + 6848689 = 3822^2 + 2617^2 .

It is a cyclic number.

It is not a de Polignac number, because 21456373 - 2⁵ = 21456341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21456313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728186 + 10728187.

It is an arithmetic number, because the mean of its divisors is an integer number (10728187).

Almost surely, 2^21456373 is an apocalyptic number.

It is an amenable number.

21456373 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456373 is an equidigital number, since it uses as much as digits as its factorization.

21456373 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 31.

The square root of 21456373 is about 4632.1024384182. The cubic root of 21456373 is about 277.8766813261.

The spelling of 21456373 in words is "twenty-one million, four hundred fifty-six thousand, three hundred seventy-three".