100031991 has 16 divisors (see below), whose sum is σ = 143976960. Its totient is φ = 61587680.

The previous prime is 100031989. The next prime is 100032011. The reversal of 100031991 is 199130001.

It is a cyclic number.

It is not a de Polignac number, because 100031991 - 2¹ = 100031989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100031891) 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, 22995 + ... + 26996.

It is an arithmetic number, because the mean of its divisors is an integer number (8998560).

Almost surely, 2^100031991 is an apocalyptic number.

100031991 is a deficient number, since it is larger than the sum of its proper divisors (43944969).

100031991 is a wasteful number, since it uses less digits than its factorization.

100031991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50046.

The product of its (nonzero) digits is 243, while the sum is 24.

The square root of 100031991 is about 10001.5994220924. The cubic root of 100031991 is about 464.2083744402.

Adding to 100031991 its reverse (199130001), we get a palindrome (299161992).

The spelling of 100031991 in words is "one hundred million, thirty-one thousand, nine hundred ninety-one".