10399991 has 4 divisors (see below), whose sum is σ = 11885712. Its totient is φ = 8914272.

The previous prime is 10399981. The next prime is 10399993. The reversal of 10399991 is 19999301.

10399991 is digitally balanced in base 3, because in such base 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 10399991 - 2⁶ = 10399927 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 (10399993) 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, 742850 + ... + 742863.

It is an arithmetic number, because the mean of its divisors is an integer number (2971428).

Almost surely, 2^10399991 is an apocalyptic number.

10399991 is a deficient number, since it is larger than the sum of its proper divisors (1485721).

10399991 is an equidigital number, since it uses as much as digits as its factorization.

10399991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1485720.

The product of its (nonzero) digits is 19683, while the sum is 41.

The square root of 10399991 is about 3224.9017039284. The cubic root of 10399991 is about 218.2785136472.

The spelling of 10399991 in words is "ten million, three hundred ninety-nine thousand, nine hundred ninety-one".