100101991 has 8 divisors (see below), whose sum is σ = 109814400. Its totient is φ = 90491640.

The previous prime is 100101973. The next prime is 100102019. The reversal of 100101991 is 199101001.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 100101991 - 2⁹ = 100101479 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 (100101941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23451 + ... + 27388.

It is an arithmetic number, because the mean of its divisors is an integer number (13726800).

Almost surely, 2^100101991 is an apocalyptic number.

100101991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

100101991 is a deficient number, since it is larger than the sum of its proper divisors (9712409).

100101991 is a wasteful number, since it uses less digits than its factorization.

100101991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51029.

The product of its (nonzero) digits is 81, while the sum is 22.

The square root of 100101991 is about 10005.0982503921. The cubic root of 100101991 is about 464.3166298399.

Adding to 100101991 its reverse (199101001), we get a palindrome (299202992).

The spelling of 100101991 in words is "one hundred million, one hundred one thousand, nine hundred ninety-one".