21725256673 has 2 divisors, whose sum is σ = 21725256674. Its totient is φ = 21725256672.

The previous prime is 21725256647. The next prime is 21725256677. The reversal of 21725256673 is 37665252712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13968403344 + 7756853329 = 118188^2 + 88073^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21725256673 is a prime.

It is not a weakly prime, because it can be changed into another prime (21725256677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10862628336 + 10862628337.

It is an arithmetic number, because the mean of its divisors is an integer number (10862628337).

Almost surely, 2^21725256673 is an apocalyptic number.

It is an amenable number.

21725256673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21725256673 is an equidigital number, since it uses as much as digits as its factorization.

21725256673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1058400, while the sum is 46.

The spelling of 21725256673 in words is "twenty-one billion, seven hundred twenty-five million, two hundred fifty-six thousand, six hundred seventy-three".