99981409 has 4 divisors (see below), whose sum is σ = 109070640. Its totient is φ = 90892180.

The previous prime is 99981389. The next prime is 99981421. The reversal of 99981409 is 90418999.

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: 90418999 = 11 ⋅8219909.

It is a cyclic number.

It is not a de Polignac number, because 99981409 - 2⁵ = 99981377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99981509) 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, 4544599 + ... + 4544620.

It is an arithmetic number, because the mean of its divisors is an integer number (27267660).

Almost surely, 2^99981409 is an apocalyptic number.

It is an amenable number.

99981409 is a deficient number, since it is larger than the sum of its proper divisors (9089231).

99981409 is a wasteful number, since it uses less digits than its factorization.

99981409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9089230.

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

The square root of 99981409 is about 9999.0704067928. The cubic root of 99981409 is about 464.1301176526.

The spelling of 99981409 in words is "ninety-nine million, nine hundred eighty-one thousand, four hundred nine".