99409981 has 4 divisors (see below), whose sum is σ = 108447264. Its totient is φ = 90372700.

The previous prime is 99409949. The next prime is 99409987. The reversal of 99409981 is 18990499.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18990499 = 11 ⋅1726409.

It is not a de Polignac number, because 99409981 - 2⁵ = 99409949 is a prime.

It is a super-2 number, since 2×99409981² = 19764688644840722, which 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 (99409987) 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, 4518625 + ... + 4518646.

It is an arithmetic number, because the mean of its divisors is an integer number (27111816).

Almost surely, 2^99409981 is an apocalyptic number.

It is an amenable number.

99409981 is a deficient number, since it is larger than the sum of its proper divisors (9037283).

99409981 is a wasteful number, since it uses less digits than its factorization.

99409981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9037282.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 99409981 is about 9970.4554058478. The cubic root of 99409981 is about 463.2442068733.

The spelling of 99409981 in words is "ninety-nine million, four hundred nine thousand, nine hundred eighty-one".