661120 has 32 divisors (see below), whose sum is σ = 1582020. Its totient is φ = 264192.

The previous prime is 661117. The next prime is 661121. The reversal of 661120 is 21166.

It can be written as a sum of positive squares in 2 ways, for example, as 627264 + 33856 = 792^2 + 184^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 661094 and 661103.

It is not an unprimeable number, because it can be changed into a prime (661121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124 + ... + 1156.

2⁶⁶¹¹²⁰ 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 661120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (791010).

661120 is an abundant number, since it is smaller than the sum of its proper divisors (920900).

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

661120 is a wasteful number, since it uses less digits than its factorization.

661120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1052 (or 1040 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 661120 is about 813.0928606254. The cubic root of 661120 is about 87.1150984647.

Adding to 661120 its reverse (21166), we get a palindrome (682286).

It can be divided in two parts, 66 and 1120, that multiplied together give a triangular number (73920 = T₃₈₄).

The spelling of 661120 in words is "six hundred sixty-one thousand, one hundred twenty".