9901891 has 4 divisors (see below), whose sum is σ = 10332432. Its totient is φ = 9471352.

The previous prime is 9901889. The next prime is 9901901. The reversal of 9901891 is 1981099.

9901891 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 9901891 - 2¹ = 9901889 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9901891.

It is not an unprimeable number, because it can be changed into a prime (9901841) 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, 215236 + ... + 215281.

It is an arithmetic number, because the mean of its divisors is an integer number (2583108).

Almost surely, 2^9901891 is an apocalyptic number.

9901891 is a deficient number, since it is larger than the sum of its proper divisors (430541).

9901891 is a wasteful number, since it uses less digits than its factorization.

9901891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430540.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 9901891 is about 3146.7270297883. The cubic root of 9901891 is about 214.7365874469.

The spelling of 9901891 in words is "nine million, nine hundred one thousand, eight hundred ninety-one".