21415199917 has 2 divisors, whose sum is σ = 21415199918. Its totient is φ = 21415199916.

The previous prime is 21415199903. The next prime is 21415199941. The reversal of 21415199917 is 71999151412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10803315721 + 10611884196 = 103939^2 + 103014^2 .

It is a cyclic number.

It is not a de Polignac number, because 21415199917 - 2²⁷ = 21280982189 is a prime.

It is a super-2 number, since 2×21415199917² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21415199947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10707599958 + 10707599959.

It is an arithmetic number, because the mean of its divisors is an integer number (10707599959).

Almost surely, 2^21415199917 is an apocalyptic number.

It is an amenable number.

21415199917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21415199917 is an equidigital number, since it uses as much as digits as its factorization.

21415199917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 204120, while the sum is 49.

The spelling of 21415199917 in words is "twenty-one billion, four hundred fifteen million, one hundred ninety-nine thousand, nine hundred seventeen".