661940 has 24 divisors (see below), whose sum is σ = 1451520. Its totient is φ = 253088.

The previous prime is 661939. The next prime is 661949. The reversal of 661940 is 49166.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661949) 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, 260 + ... + 1179.

It is an arithmetic number, because the mean of its divisors is an integer number (60480).

2⁶⁶¹⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

661940 is an abundant number, since it is smaller than the sum of its proper divisors (789580).

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

661940 is a wasteful number, since it uses less digits than its factorization.

661940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1471 (or 1469 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 661940 is about 813.5969518134. The cubic root of 661940 is about 87.1511004347.

The spelling of 661940 in words is "six hundred sixty-one thousand, nine hundred forty".