661506 has 8 divisors (see below), whose sum is σ = 1323024. Its totient is φ = 220500.

The previous prime is 661483. The next prime is 661513. The reversal of 661506 is 605166.

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

661506 is an admirable number.

It is an unprimeable number.

661506 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55120 + ... + 55131.

It is an arithmetic number, because the mean of its divisors is an integer number (165378).

2⁶⁶¹⁵⁰⁶ is an apocalyptic number.

661506 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661506 is a wasteful number, since it uses less digits than its factorization.

661506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110256.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 661506 is about 813.3301912508. The cubic root of 661506 is about 87.1320494397.

It can be divided in two parts, 66150 and 6, that multiplied together give a square (396900 = 630²).

The spelling of 661506 in words is "six hundred sixty-one thousand, five hundred six".