661404874240 has 320 divisors, whose sum is σ = 1753248499200. Its totient is φ = 237298647040.

The previous prime is 661404874201. The next prime is 661404874261. The reversal of 661404874240 is 42478404166.

It is a tau number, because it is divible by the number of its divisors (320).

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, 1104181461 + ... + 1104182059.

It is an arithmetic number, because the mean of its divisors is an integer number (5478901560).

Almost surely, 2^661404874240 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 661404874240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (876624249600).

661404874240 is an abundant number, since it is smaller than the sum of its proper divisors (1091843624960).

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

661404874240 is a wasteful number, since it uses less digits than its factorization.

661404874240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1093 (or 1077 counting only the distinct ones).

The product of its (nonzero) digits is 1032192, while the sum is 46.

The spelling of 661404874240 in words is "six hundred sixty-one billion, four hundred four million, eight hundred seventy-four thousand, two hundred forty".