661626 has 48 divisors (see below), whose sum is σ = 1684800. Its totient is φ = 183744.

The previous prime is 661621. The next prime is 661663. The reversal of 661626 is 626166.

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661626.

It is not an unprimeable number, because it can be changed into a prime (661621) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7390 + ... + 7478.

It is an arithmetic number, because the mean of its divisors is an integer number (35100).

2⁶⁶¹⁶²⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661626, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (842400).

661626 is an abundant number, since it is smaller than the sum of its proper divisors (1023174).

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

661626 is a wasteful number, since it uses less digits than its factorization.

661626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163 (or 160 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 661626 is about 813.4039586823. The cubic root of 661626 is about 87.1373178291.

The spelling of 661626 in words is "six hundred sixty-one thousand, six hundred twenty-six".