101991031 has 4 divisors (see below), whose sum is σ = 107359000. Its totient is φ = 96623064.

The previous prime is 101991017. The next prime is 101991047. The reversal of 101991031 is 130199101.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 130199101 = 31 ⋅4199971.

It is a cyclic number.

It is not a de Polignac number, because 101991031 - 2⁹ = 101990519 is a prime.

It is a super-2 number, since 2×101991031² = 20804340808885922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 101990987 and 101991005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (101991061) 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, 2683956 + ... + 2683993.

It is an arithmetic number, because the mean of its divisors is an integer number (26839750).

Almost surely, 2^101991031 is an apocalyptic number.

101991031 is a deficient number, since it is larger than the sum of its proper divisors (5367969).

101991031 is an equidigital number, since it uses as much as digits as its factorization.

101991031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5367968.

The product of its (nonzero) digits is 243, while the sum is 25.

The square root of 101991031 is about 10099.0608969349. The cubic root of 101991031 is about 467.2191776248.

The spelling of 101991031 in words is "one hundred one million, nine hundred ninety-one thousand, thirty-one".