21708326635973 has 2 divisors, whose sum is σ = 21708326635974. Its totient is φ = 21708326635972.

The previous prime is 21708326635951. The next prime is 21708326635979. The reversal of 21708326635973 is 37953662380712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16434405199969 + 5273921436004 = 4053937^2 + 2296502^2 .

It is a cyclic number.

It is not a de Polignac number, because 21708326635973 - 2²² = 21708322441669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21708326635979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854163317986 + 10854163317987.

It is an arithmetic number, because the mean of its divisors is an integer number (10854163317987).

Almost surely, 2^{21708326635973} is an apocalyptic number.

It is an amenable number.

21708326635973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21708326635973 is an equidigital number, since it uses as much as digits as its factorization.

21708326635973 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 68584320, while the sum is 62.

The spelling of 21708326635973 in words is "twenty-one trillion, seven hundred eight billion, three hundred twenty-six million, six hundred thirty-five thousand, nine hundred seventy-three".