400905 has 24 divisors (see below), whose sum is σ = 711360. Its totient is φ = 208800.

The previous prime is 400903. The next prime is 400927. The reversal of 400905 is 509004.

It is not a de Polignac number, because 400905 - 2¹ = 400903 is a prime.

It is a Curzon number.

400905 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400903) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2580 + ... + 2730.

It is an arithmetic number, because the mean of its divisors is an integer number (29640).

2⁴⁰⁰⁹⁰⁵ is an apocalyptic number.

400905 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

400905 is a deficient number, since it is larger than the sum of its proper divisors (310455).

400905 is a wasteful number, since it uses less digits than its factorization.

400905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 400905 is about 633.1705931264. The cubic root of 400905 is about 73.7361555934.

Adding to 400905 its reverse (509004), we get a palindrome (909909).

The spelling of 400905 in words is "four hundred thousand, nine hundred five".