400191 has 16 divisors (see below), whose sum is σ = 594048. Its totient is φ = 237600.

The previous prime is 400187. The next prime is 400199. The reversal of 400191 is 191004.

It is not a de Polignac number, because 400191 - 2² = 400187 is a prime.

It is an Ulam number.

400191 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 400191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400199) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2121 + ... + 2301.

It is an arithmetic number, because the mean of its divisors is an integer number (37128).

2⁴⁰⁰¹⁹¹ is an apocalyptic number.

400191 is a deficient number, since it is larger than the sum of its proper divisors (193857).

400191 is a wasteful number, since it uses less digits than its factorization.

400191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 400191 is about 632.6065127708. The cubic root of 400191 is about 73.6923556069.

Adding to 400191 its reverse (191004), we get a palindrome (591195).

The spelling of 400191 in words is "four hundred thousand, one hundred ninety-one".