21466715381 has 2 divisors, whose sum is σ = 21466715382. Its totient is φ = 21466715380.

The previous prime is 21466715357. The next prime is 21466715393. The reversal of 21466715381 is 18351766412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21033700900 + 433014481 = 145030^2 + 20809^2 .

It is a cyclic number.

It is not a de Polignac number, because 21466715381 - 2⁶ = 21466715317 is a prime.

It is a super-2 number, since 2×21466715381² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21466715311) 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, 10733357690 + 10733357691.

It is an arithmetic number, because the mean of its divisors is an integer number (10733357691).

Almost surely, 2^21466715381 is an apocalyptic number.

It is an amenable number.

21466715381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21466715381 is an equidigital number, since it uses as much as digits as its factorization.

21466715381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 44.

The spelling of 21466715381 in words is "twenty-one billion, four hundred sixty-six million, seven hundred fifteen thousand, three hundred eighty-one".