9951391 has 4 divisors (see below), whose sum is σ = 9988384. Its totient is φ = 9914400.

The previous prime is 9951377. The next prime is 9951401. The reversal of 9951391 is 1931599.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1931599 = 1087 ⋅1777.

It is a cyclic number.

It is not a de Polignac number, because 9951391 - 2⁹ = 9950879 is a prime.

It is a Duffinian number.

9951391 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 9951391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9951301) 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, 18090 + ... + 18631.

It is an arithmetic number, because the mean of its divisors is an integer number (2497096).

It is the magic constant of a 271 × 271 magic square.

Almost surely, 2^9951391 is an apocalyptic number.

9951391 is a deficient number, since it is larger than the sum of its proper divisors (36993).

9951391 is a wasteful number, since it uses less digits than its factorization.

9951391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36992.

The product of its digits is 10935, while the sum is 37.

The square root of 9951391 is about 3154.5825397349. The cubic root of 9951391 is about 215.0938187987.

The spelling of 9951391 in words is "nine million, nine hundred fifty-one thousand, three hundred ninety-one".