99781817 has 2 divisors, whose sum is σ = 99781818. Its totient is φ = 99781816.

The previous prime is 99781813. The next prime is 99781849. The reversal of 99781817 is 71818799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 98089216 + 1692601 = 9904^2 + 1301^2 .

It is a cyclic number.

It is not a de Polignac number, because 99781817 - 2² = 99781813 is a prime.

It is a super-2 number, since 2×99781817² = 19912822007642978, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (99781813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49890908 + 49890909.

It is an arithmetic number, because the mean of its divisors is an integer number (49890909).

Almost surely, 2^99781817 is an apocalyptic number.

It is an amenable number.

99781817 is a deficient number, since it is larger than the sum of its proper divisors (1).

99781817 is an equidigital number, since it uses as much as digits as its factorization.

99781817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 254016, while the sum is 50.

The square root of 99781817 is about 9989.0848930220. The cubic root of 99781817 is about 463.8210656296.

The spelling of 99781817 in words is "ninety-nine million, seven hundred eighty-one thousand, eight hundred seventeen".