9991901 has 4 divisors (see below), whose sum is σ = 10132704. Its totient is φ = 9851100.

The previous prime is 9991879. The next prime is 9991939. The reversal of 9991901 is 1091999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1091999 = 307 ⋅3557.

It is a cyclic number.

It is not a de Polignac number, because 9991901 - 2⁶ = 9991837 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 (9991301) 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, 70295 + ... + 70436.

It is an arithmetic number, because the mean of its divisors is an integer number (2533176).

Almost surely, 2^9991901 is an apocalyptic number.

It is an amenable number.

9991901 is a deficient number, since it is larger than the sum of its proper divisors (140803).

9991901 is a wasteful number, since it uses less digits than its factorization.

9991901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140802.

The product of its (nonzero) digits is 6561, while the sum is 38.

The square root of 9991901 is about 3160.9968364426. The cubic root of 9991901 is about 215.3852907390.

The spelling of 9991901 in words is "nine million, nine hundred ninety-one thousand, nine hundred one".