10401991 has 4 divisors (see below), whose sum is σ = 10408552. Its totient is φ = 10395432.

The previous prime is 10401973. The next prime is 10402031. The reversal of 10401991 is 19910401.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 10401991 - 2⁷ = 10401863 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10401901) 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, 745 + ... + 4621.

It is an arithmetic number, because the mean of its divisors is an integer number (2602138).

Almost surely, 2^10401991 is an apocalyptic number.

10401991 is a deficient number, since it is larger than the sum of its proper divisors (6561).

10401991 is an equidigital number, since it uses as much as digits as its factorization.

10401991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6560.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 10401991 is about 3225.2117759924. The cubic root of 10401991 is about 218.2925049749.

The spelling of 10401991 in words is "ten million, four hundred one thousand, nine hundred ninety-one".