21387302617 has 2 divisors, whose sum is σ = 21387302618. Its totient is φ = 21387302616.

The previous prime is 21387302611. The next prime is 21387302621. The reversal of 21387302617 is 71620378312.

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., 17239427401 + 4147875216 = 131299^2 + 64404^2 .

It is a cyclic number.

It is not a de Polignac number, because 21387302617 - 2³ = 21387302609 is a prime.

It is a super-2 number, since 2×21387302617² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21387302617.

It is not a weakly prime, because it can be changed into another prime (21387302611) 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, 10693651308 + 10693651309.

It is an arithmetic number, because the mean of its divisors is an integer number (10693651309).

Almost surely, 2^21387302617 is an apocalyptic number.

It is an amenable number.

21387302617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21387302617 is an equidigital number, since it uses as much as digits as its factorization.

21387302617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84672, while the sum is 40.

The spelling of 21387302617 in words is "twenty-one billion, three hundred eighty-seven million, three hundred two thousand, six hundred seventeen".