100999991 has 16 divisors (see below), whose sum is σ = 109549440. Its totient is φ = 92806560.

The previous prime is 100999981. The next prime is 100999993. The reversal of 100999991 is 199999001.

It is a cyclic number.

It is not a de Polignac number, because 100999991 - 2¹⁴ = 100983607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100999993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 147536 + ... + 148218.

It is an arithmetic number, because the mean of its divisors is an integer number (6846840).

Almost surely, 2^100999991 is an apocalyptic number.

100999991 is a deficient number, since it is larger than the sum of its proper divisors (8549449).

100999991 is a wasteful number, since it uses less digits than its factorization.

100999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 926.

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

The square root of 100999991 is about 10049.8751733541. The cubic root of 100999991 is about 465.7009369477.

The spelling of 100999991 in words is "one hundred million, nine hundred ninety-nine thousand, nine hundred ninety-one".