99995991 has 4 divisors (see below), whose sum is σ = 133327992. Its totient is φ = 66663992.

The previous prime is 99995983. The next prime is 99995999. The reversal of 99995991 is 19959999.

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

It is an interprime number because it is at equal distance from previous prime (99995983) and next prime (99995999).

It is a cyclic number.

It is not a de Polignac number, because 99995991 - 2³ = 99995983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99995999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16665996 + ... + 16666001.

It is an arithmetic number, because the mean of its divisors is an integer number (33331998).

Almost surely, 2^99995991 is an apocalyptic number.

99995991 is a deficient number, since it is larger than the sum of its proper divisors (33332001).

99995991 is a wasteful number, since it uses less digits than its factorization.

99995991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33332000.

The product of its digits is 2657205, while the sum is 60.

The square root of 99995991 is about 9999.7995479909. The cubic root of 99995991 is about 464.1526805685.

The spelling of 99995991 in words is "ninety-nine million, nine hundred ninety-five thousand, nine hundred ninety-one".