10101991891 has 4 divisors (see below), whose sum is σ = 10123810912. Its totient is φ = 10080172872.

The previous prime is 10101991883. The next prime is 10101991919. The reversal of 10101991891 is 19819910101.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19819910101 = 439 ⋅45147859.

It is a cyclic number.

It is not a de Polignac number, because 10101991891 - 2³ = 10101991883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10101991811) 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, 10908816 + ... + 10909741.

It is an arithmetic number, because the mean of its divisors is an integer number (2530952728).

Almost surely, 2^10101991891 is an apocalyptic number.

10101991891 is a deficient number, since it is larger than the sum of its proper divisors (21819021).

10101991891 is an equidigital number, since it uses as much as digits as its factorization.

10101991891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21819020.

The product of its (nonzero) digits is 5832, while the sum is 40.

The spelling of 10101991891 in words is "ten billion, one hundred one million, nine hundred ninety-one thousand, eight hundred ninety-one".