99117917981 has 4 divisors (see below), whose sum is σ = 99142353372. Its totient is φ = 99093482592.

The previous prime is 99117917963. The next prime is 99117918001. The reversal of 99117917981 is 18971971199.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 76650905881 + 22467012100 = 276859^2 + 149890^2 .

It is a cyclic number.

It is not a de Polignac number, because 99117917981 - 2⁶ = 99117917917 is a prime.

It is a super-2 number, since 2×99117917981² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99117617981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12211610 + ... + 12219723.

It is an arithmetic number, because the mean of its divisors is an integer number (24785588343).

Almost surely, 2^99117917981 is an apocalyptic number.

It is an amenable number.

99117917981 is a deficient number, since it is larger than the sum of its proper divisors (24435391).

99117917981 is a wasteful number, since it uses less digits than its factorization.

99117917981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24435390.

The product of its digits is 2571912, while the sum is 62.

The spelling of 99117917981 in words is "ninety-nine billion, one hundred seventeen million, nine hundred seventeen thousand, nine hundred eighty-one".