661240 has 32 divisors (see below), whose sum is σ = 1517760. Its totient is φ = 259200.

The previous prime is 661237. The next prime is 661253. The reversal of 661240 is 42166.

661240 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2305 + ... + 2575.

It is an arithmetic number, because the mean of its divisors is an integer number (47430).

2⁶⁶¹²⁴⁰ 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 661240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (758880).

661240 is an abundant number, since it is smaller than the sum of its proper divisors (856520).

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

661240 is a wasteful number, since it uses less digits than its factorization.

661240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343 (or 339 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 661240 is about 813.1666495867. The cubic root of 661240 is about 87.1203689044.

The spelling of 661240 in words is "six hundred sixty-one thousand, two hundred forty".