661144 has 24 divisors (see below), whose sum is σ = 1364580. Its totient is φ = 300080.

The previous prime is 661139. The next prime is 661183. The reversal of 661144 is 441166.

It is a super-2 number, since 2×661144² = 874222777472, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a zygodrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 627 + ... + 1309.

2⁶⁶¹¹⁴⁴ 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 661144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (682290).

661144 is an abundant number, since it is smaller than the sum of its proper divisors (703436).

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

661144 is a wasteful number, since it uses less digits than its factorization.

661144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 711 (or 696 counting only the distinct ones).

The product of its digits is 576, while the sum is 22.

The square root of 661144 is about 813.1076189534. The cubic root of 661144 is about 87.1161526036.

Adding to 661144 its sum of digits (22), we get a palindrome (661166).

The spelling of 661144 in words is "six hundred sixty-one thousand, one hundred forty-four".