21810943673 has 2 divisors, whose sum is σ = 21810943674. Its totient is φ = 21810943672.

The previous prime is 21810943669. The next prime is 21810943697. The reversal of 21810943673 is 37634901812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12742571689 + 9068371984 = 112883^2 + 95228^2 .

It is a cyclic number.

It is not a de Polignac number, because 21810943673 - 2² = 21810943669 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21810943663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10905471836 + 10905471837.

It is an arithmetic number, because the mean of its divisors is an integer number (10905471837).

Almost surely, 2^21810943673 is an apocalyptic number.

It is an amenable number.

21810943673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21810943673 is an equidigital number, since it uses as much as digits as its factorization.

21810943673 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 44.

The spelling of 21810943673 in words is "twenty-one billion, eight hundred ten million, nine hundred forty-three thousand, six hundred seventy-three".