661100 has 36 divisors (see below), whose sum is σ = 1567608. Its totient is φ = 240000.

The previous prime is 661099. The next prime is 661103. The reversal of 661100 is 1166.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (661103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 800 + ... + 1400.

2⁶⁶¹¹⁰⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (783804).

661100 is an abundant number, since it is smaller than the sum of its proper divisors (906508).

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

661100 is a wasteful number, since it uses less digits than its factorization.

661100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 626 (or 619 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 661100 is about 813.0805618141. The cubic root of 661100 is about 87.1142199960.

Adding to 661100 its reverse (1166), we get a palindrome (662266).

The spelling of 661100 in words is "six hundred sixty-one thousand, one hundred".