99976781 has 2 divisors, whose sum is σ = 99976782. Its totient is φ = 99976780.

The previous prime is 99976777. The next prime is 99976787. The reversal of 99976781 is 18767999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94264681 + 5712100 = 9709^2 + 2390^2 .

It is an emirp because it is prime and its reverse (18767999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99976781 - 2² = 99976777 is a prime.

It is a super-2 number, since 2×99976781² = 19990713478243922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen 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 (99976787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49988390 + 49988391.

It is an arithmetic number, because the mean of its divisors is an integer number (49988391).

Almost surely, 2^99976781 is an apocalyptic number.

It is an amenable number.

99976781 is a deficient number, since it is larger than the sum of its proper divisors (1).

99976781 is an equidigital number, since it uses as much as digits as its factorization.

99976781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1714608, while the sum is 56.

The square root of 99976781 is about 9998.8389826019. The cubic root of 99976781 is about 464.1229562301.

It can be divided in two parts, 99976 and 781, that multiplied together give a triangular number (78081256 = T₁₂₄₉₆).

The spelling of 99976781 in words is "ninety-nine million, nine hundred seventy-six thousand, seven hundred eighty-one".