21297673 has 2 divisors, whose sum is σ = 21297674. Its totient is φ = 21297672.

The previous prime is 21297667. The next prime is 21297691. The reversal of 21297673 is 37679212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21233664 + 64009 = 4608^2 + 253^2 .

It is a cyclic number.

It is not a de Polignac number, because 21297673 - 2⁵ = 21297641 is a prime.

It is not a weakly prime, because it can be changed into another prime (21297973) 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, 10648836 + 10648837.

It is an arithmetic number, because the mean of its divisors is an integer number (10648837).

Almost surely, 2^21297673 is an apocalyptic number.

It is an amenable number.

21297673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21297673 is an equidigital number, since it uses as much as digits as its factorization.

21297673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31752, while the sum is 37.

The square root of 21297673 is about 4614.9401946287. The cubic root of 21297673 is about 277.1898892163.

The spelling of 21297673 in words is "twenty-one million, two hundred ninety-seven thousand, six hundred seventy-three".