20878467917 has 2 divisors, whose sum is σ = 20878467918. Its totient is φ = 20878467916.

The previous prime is 20878467871. The next prime is 20878467919. The reversal of 20878467917 is 71976487802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17991125161 + 2887342756 = 134131^2 + 53734^2 .

It is a cyclic number.

It is not a de Polignac number, because 20878467917 - 2¹⁴ = 20878451533 is a prime.

It is a super-2 number, since 2×20878467917² (a number of 21 digits) contains 22 as substring.

Together with 20878467919, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20878467919) 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, 10439233958 + 10439233959.

It is an arithmetic number, because the mean of its divisors is an integer number (10439233959).

Almost surely, 2^20878467917 is an apocalyptic number.

It is an amenable number.

20878467917 is a deficient number, since it is larger than the sum of its proper divisors (1).

20878467917 is an equidigital number, since it uses as much as digits as its factorization.

20878467917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9483264, while the sum is 59.

The spelling of 20878467917 in words is "twenty billion, eight hundred seventy-eight million, four hundred sixty-seven thousand, nine hundred seventeen".