999995100781 has 2 divisors, whose sum is σ = 999995100782. Its totient is φ = 999995100780.

The previous prime is 999995100779. The next prime is 999995100821. The reversal of 999995100781 is 187001599999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 983131740900 + 16863359881 = 991530^2 + 129859^2 .

It is an emirp because it is prime and its reverse (187001599999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999995100781 - 2¹ = 999995100779 is a prime.

It is a super-2 number, since 2×999995100781² (a number of 25 digits) contains 22 as substring.

Together with 999995100779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999995100721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499997550390 + 499997550391.

It is an arithmetic number, because the mean of its divisors is an integer number (499997550391).

Almost surely, 2^999995100781 is an apocalyptic number.

999995100781 is the 447213-rd centered decagonal number.

It is an amenable number.

999995100781 is a deficient number, since it is larger than the sum of its proper divisors (1).

999995100781 is an equidigital number, since it uses as much as digits as its factorization.

999995100781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16533720, while the sum is 67.

The spelling of 999995100781 in words is "nine hundred ninety-nine billion, nine hundred ninety-five million, one hundred thousand, seven hundred eighty-one".