40431209 has 32 divisors (see below), whose sum is σ = 51819264. Its totient is φ = 30700800.

The previous prime is 40431199. The next prime is 40431241. The reversal of 40431209 is 90213404.

It is not a de Polignac number, because 40431209 - 2¹⁶ = 40365673 is a prime.

It is a super-2 number, since 2×40431209² = 3269365322403362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (40431109) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 400259 + ... + 400359.

It is an arithmetic number, because the mean of its divisors is an integer number (1619352).

Almost surely, 2^40431209 is an apocalyptic number.

It is an amenable number.

40431209 is a deficient number, since it is larger than the sum of its proper divisors (11388055).

40431209 is a wasteful number, since it uses less digits than its factorization.

40431209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 40431209 is about 6358.5540022870. The cubic root of 40431209 is about 343.2197279164.

It can be divided in two parts, 404 and 31209, that added together give a palindrome (31613).

The spelling of 40431209 in words is "forty million, four hundred thirty-one thousand, two hundred nine".