405681 has 8 divisors (see below), whose sum is σ = 559680. Its totient is φ = 261072.

The previous prime is 405679. The next prime is 405683. The reversal of 405681 is 186504.

It is an interprime number because it is at equal distance from previous prime (405679) and next prime (405683).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 405681 - 2¹ = 405679 is a prime.

It is a super-2 number, since 2×405681² = 329154147522, which contains 22 as substring.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 405681.

It is not an unprimeable number, because it can be changed into a prime (405683) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2245 + ... + 2418.

It is an arithmetic number, because the mean of its divisors is an integer number (69960).

2⁴⁰⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

405681 is a deficient number, since it is larger than the sum of its proper divisors (153999).

405681 is a wasteful number, since it uses less digits than its factorization.

405681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4695.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 405681 is about 636.9309224712. The cubic root of 405681 is about 74.0278079079.

The spelling of 405681 in words is "four hundred five thousand, six hundred eighty-one".