661766140 has 96 divisors (see below), whose sum is σ = 1698931584. Its totient is φ = 211353600.

The previous prime is 661766101. The next prime is 661766153. The reversal of 661766140 is 41667166.

It is a self number, because there is not a number n which added to its sum of digits gives 661766140.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 239004 + ... + 241756.

It is an arithmetic number, because the mean of its divisors is an integer number (17697204).

Almost surely, 2^661766140 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 661766140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (849465792).

661766140 is an abundant number, since it is smaller than the sum of its proper divisors (1037165444).

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

661766140 is a wasteful number, since it uses less digits than its factorization.

661766140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2887 (or 2885 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 661766140 is about 25724.8156455979. The cubic root of 661766140 is about 871.4346962368.

The spelling of 661766140 in words is "six hundred sixty-one million, seven hundred sixty-six thousand, one hundred forty".