21186665741 has 2 divisors, whose sum is σ = 21186665742. Its totient is φ = 21186665740.

The previous prime is 21186665737. The next prime is 21186665767. The reversal of 21186665741 is 14756668112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19090948900 + 2095716841 = 138170^2 + 45779^2 .

It is a cyclic number.

It is not a de Polignac number, because 21186665741 - 2² = 21186665737 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21186665771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10593332870 + 10593332871.

It is an arithmetic number, because the mean of its divisors is an integer number (10593332871).

Almost surely, 2^21186665741 is an apocalyptic number.

It is an amenable number.

21186665741 is a deficient number, since it is larger than the sum of its proper divisors (1).

21186665741 is an equidigital number, since it uses as much as digits as its factorization.

21186665741 is an evil number, because the sum of its binary digits is even.

The product of its digits is 483840, while the sum is 47.

The spelling of 21186665741 in words is "twenty-one billion, one hundred eighty-six million, six hundred sixty-five thousand, seven hundred forty-one".