9919684099809 has 27 divisors (see below), whose sum is σ = 15749599186867. Its totient is φ = 6011866766400.

The previous prime is 9919684099781. The next prime is 9919684099823. The reversal of 9919684099809 is 9089904869199.

The square root of 9919684099809 is 3149553.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 8701927709409 + 1217756390400 = 2949903^2 + 1103520^2 .

It is not a de Polignac number, because 9919684099809 - 2⁴¹ = 7720660844257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9919684099309) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 103887529 + ... + 103982969.

Almost surely, 2^{9919684099809} is an apocalyptic number.

9919684099809 is a gapful number since it is divisible by the number (99) formed by its first and last digit.

9919684099809 is the 3149553-rd square number.

9919684099809 is the 1574777-th centered octagonal number.

It is an amenable number.

9919684099809 is a deficient number, since it is larger than the sum of its proper divisors (5829915087058).

9919684099809 is an frugal number, since it uses more digits than its factorization.

9919684099809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190910 (or 95455 counting only the distinct ones).

The product of its (nonzero) digits is 816293376, while the sum is 81.

Multiplying 9919684099809 by its sum of digits (81), we get a square (803494412084529 = 28345977²).

The spelling of 9919684099809 in words is "nine trillion, nine hundred nineteen billion, six hundred eighty-four million, ninety-nine thousand, eight hundred nine".