405987 has 4 divisors (see below), whose sum is σ = 541320. Its totient is φ = 270656.

The previous prime is 405967. The next prime is 405989. The reversal of 405987 is 789504.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 405987 - 2⁸ = 405731 is a prime.

It is a D-number.

It is a zygodrome in base 2.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 405987.

It is not an unprimeable number, because it can be changed into a prime (405989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67662 + ... + 67667.

It is an arithmetic number, because the mean of its divisors is an integer number (135330).

2⁴⁰⁵⁹⁸⁷ is an apocalyptic number.

405987 is a deficient number, since it is larger than the sum of its proper divisors (135333).

405987 is a wasteful number, since it uses less digits than its factorization.

405987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135332.

The product of its (nonzero) digits is 10080, while the sum is 33.

The square root of 405987 is about 637.1710916230. The cubic root of 405987 is about 74.0464159736.

The spelling of 405987 in words is "four hundred five thousand, nine hundred eighty-seven".