991399101 has 24 divisors (see below), whose sum is σ = 1660529472. Its totient is φ = 515011200.

The previous prime is 991399093. The next prime is 991399109. The reversal of 991399101 is 101993199.

It is an interprime number because it is at equal distance from previous prime (991399093) and next prime (991399109).

It is not a de Polignac number, because 991399101 - 2³ = 991399093 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991399109) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 192540 + ... + 197621.

It is an arithmetic number, because the mean of its divisors is an integer number (69188728).

Almost surely, 2^991399101 is an apocalyptic number.

It is an amenable number.

991399101 is a deficient number, since it is larger than the sum of its proper divisors (669130371).

991399101 is a wasteful number, since it uses less digits than its factorization.

991399101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390193 (or 390182 counting only the distinct ones).

The product of its (nonzero) digits is 19683, while the sum is 42.

The square root of 991399101 is about 31486.4907698524. The cubic root of 991399101 is about 997.1247746690.

The spelling of 991399101 in words is "nine hundred ninety-one million, three hundred ninety-nine thousand, one hundred one".