661340 has 24 divisors (see below), whose sum is σ = 1422960. Its totient is φ = 258048.

The previous prime is 661327. The next prime is 661343. The reversal of 661340 is 43166.

661340 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 476 + ... + 1244.

It is an arithmetic number, because the mean of its divisors is an integer number (59290).

2⁶⁶¹³⁴⁰ 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 661340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (711480).

661340 is an abundant number, since it is smaller than the sum of its proper divisors (761620).

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

661340 is a wasteful number, since it uses less digits than its factorization.

661340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821 (or 819 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 661340 is about 813.2281352732. The cubic root of 661340 is about 87.1247604505.

It can be divided in two parts, 661 and 340, that added together give a palindrome (1001).

The spelling of 661340 in words is "six hundred sixty-one thousand, three hundred forty".