99181681 has 9 divisors (see below), whose sum is σ = 103921419. Its totient is φ = 94650336.

The previous prime is 99181661. The next prime is 99181699. The reversal of 99181681 is 18618199.

It is a happy number.

The square root of 99181681 is 9959.

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., 11122225 + 88059456 = 3335^2 + 9384^2 .

It is not a de Polignac number, because 99181681 - 2¹³ = 99173489 is a prime.

It is a super-2 number, since 2×99181681² = 19674011691971522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99181601) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 228841 + ... + 229273.

Almost surely, 2^99181681 is an apocalyptic number.

99181681 is the 9959-th square number.

99181681 is the 4980-th centered octagonal number.

It is an amenable number.

99181681 is a deficient number, since it is larger than the sum of its proper divisors (4739738).

99181681 is an frugal number, since it uses more digits than its factorization.

99181681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912 (or 456 counting only the distinct ones).

The product of its digits is 31104, while the sum is 43.

The cubic root of 99181681 is about 462.8893138842.

The spelling of 99181681 in words is "ninety-nine million, one hundred eighty-one thousand, six hundred eighty-one".