405989 has 2 divisors, whose sum is σ = 405990. Its totient is φ = 405988.

The previous prime is 405967. The next prime is 405991. The reversal of 405989 is 989504.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 293764 + 112225 = 542^2 + 335^2 .

It is a cyclic number.

It is not a de Polignac number, because 405989 - 2¹⁶ = 340453 is a prime.

Together with 405991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (405949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202994 + 202995.

It is an arithmetic number, because the mean of its divisors is an integer number (202995).

2⁴⁰⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

405989 is a deficient number, since it is larger than the sum of its proper divisors (1).

405989 is an equidigital number, since it uses as much as digits as its factorization.

405989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 405989 is about 637.1726610582. The cubic root of 405989 is about 74.0465375641.

The spelling of 405989 in words is "four hundred five thousand, nine hundred eighty-nine".