40491 has 12 divisors (see below), whose sum is σ = 63960. Its totient is φ = 24480.

The previous prime is 40487. The next prime is 40493. The reversal of 40491 is 19404.

It is not a de Polignac number, because 40491 - 2² = 40487 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (40493) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 106 + ... + 303.

It is an arithmetic number, because the mean of its divisors is an integer number (5330).

2⁴⁰⁴⁹¹ is an apocalyptic number.

40491 is a deficient number, since it is larger than the sum of its proper divisors (23469).

40491 is a wasteful number, since it uses less digits than its factorization.

40491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426 (or 423 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 40491 is about 201.2237560528. The cubic root of 40491 is about 34.3388832787.

Adding to 40491 its reverse (19404), we get a palindrome (59895).

The spelling of 40491 in words is "forty thousand, four hundred ninety-one".