9951691 has 4 divisors (see below), whose sum is σ = 9974800. Its totient is φ = 9928584.

The previous prime is 9951637. The next prime is 9951701. The reversal of 9951691 is 1961599.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1961599 = 863 ⋅2273.

It is a cyclic number.

It is not a de Polignac number, because 9951691 - 2⁷ = 9951563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9951191) 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, 10896 + ... + 11773.

It is an arithmetic number, because the mean of its divisors is an integer number (2493700).

Almost surely, 2^9951691 is an apocalyptic number.

9951691 is a deficient number, since it is larger than the sum of its proper divisors (23109).

9951691 is a wasteful number, since it uses less digits than its factorization.

9951691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23108.

The product of its digits is 21870, while the sum is 40.

The square root of 9951691 is about 3154.6300892498. The cubic root of 9951691 is about 215.0959802217.

The spelling of 9951691 in words is "nine million, nine hundred fifty-one thousand, six hundred ninety-one".