99400891 has 4 divisors (see below), whose sum is σ = 99420832. Its totient is φ = 99380952.

The previous prime is 99400841. The next prime is 99400897. The reversal of 99400891 is 19800499.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99400891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99400897) 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, 4981 + ... + 14953.

It is an arithmetic number, because the mean of its divisors is an integer number (24855208).

Almost surely, 2^99400891 is an apocalyptic number.

99400891 is a deficient number, since it is larger than the sum of its proper divisors (19941).

99400891 is an equidigital number, since it uses as much as digits as its factorization.

99400891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19940.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 99400891 is about 9969.9995486459. Note that the first 3 decimals coincide. The cubic root of 99400891 is about 463.2300868350.

The spelling of 99400891 in words is "ninety-nine million, four hundred thousand, eight hundred ninety-one".