66406 has 4 divisors (see below), whose sum is σ = 99612. Its totient is φ = 33202.

The previous prime is 66403. The next prime is 66413. The reversal of 66406 is 60466.

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

It is a nialpdrome in base 5.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16600 + ... + 16603.

It is an arithmetic number, because the mean of its divisors is an integer number (24903).

2⁶⁶⁴⁰⁶ is an apocalyptic number.

66406 is a deficient number, since it is larger than the sum of its proper divisors (33206).

66406 is a wasteful number, since it uses less digits than its factorization.

66406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33205.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 66406 is about 257.6936165294. The cubic root of 66406 is about 40.4950966985.

It can be divided in two parts, 66 and 406, that multiplied together give a triangular number (26796 = T₂₃₁).

The spelling of 66406 in words is "sixty-six thousand, four hundred six".