99778509 has 24 divisors (see below), whose sum is σ = 148337280. Its totient is φ = 64597248.

The previous prime is 99778507. The next prime is 99778537. The reversal of 99778509 is 90587799.

It is not a de Polignac number, because 99778509 - 2¹ = 99778507 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99778507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57949 + ... + 59645.

It is an arithmetic number, because the mean of its divisors is an integer number (6180720).

Almost surely, 2^99778509 is an apocalyptic number.

It is an amenable number.

99778509 is a deficient number, since it is larger than the sum of its proper divisors (48558771).

99778509 is a wasteful number, since it uses less digits than its factorization.

99778509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1889 (or 1886 counting only the distinct ones).

The product of its (nonzero) digits is 1428840, while the sum is 54.

The square root of 99778509 is about 9988.9193109165. The cubic root of 99778509 is about 463.8159399895.

The spelling of 99778509 in words is "ninety-nine million, seven hundred seventy-eight thousand, five hundred nine".