991099901 has 4 divisors (see below), whose sum is σ = 1081199904. Its totient is φ = 900999900.

The previous prime is 991099891. The next prime is 991099919. The reversal of 991099901 is 109990199.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991099901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991099961) 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, 45049985 + ... + 45050006.

It is an arithmetic number, because the mean of its divisors is an integer number (270299976).

Almost surely, 2^991099901 is an apocalyptic number.

It is an amenable number.

991099901 is a deficient number, since it is larger than the sum of its proper divisors (90100003).

991099901 is a wasteful number, since it uses less digits than its factorization.

991099901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90100002.

The product of its (nonzero) digits is 59049, while the sum is 47.

The square root of 991099901 is about 31481.7391673332. The cubic root of 991099901 is about 997.0244552485.

The spelling of 991099901 in words is "nine hundred ninety-one million, ninety-nine thousand, nine hundred one".