661318655040 has 560 divisors, whose sum is σ = 2438074619904. Its totient is φ = 169977139200.

The previous prime is 661318655033. The next prime is 661318655083. The reversal of 661318655040 is 40556813166.

661318655040 is a `hidden beast` number, since 6 + 6 + 13 + 1 + 86 + 550 + 4 + 0 = 666.

661318655040 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 (45).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 217752402 + ... + 217755438.

Almost surely, 2^661318655040 is an apocalyptic number.

661318655040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661318655040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1219037309952).

661318655040 is an abundant number, since it is smaller than the sum of its proper divisors (1776755964864).

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

661318655040 is a wasteful number, since it uses less digits than its factorization.

661318655040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3368 (or 3349 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The spelling of 661318655040 in words is "six hundred sixty-one billion, three hundred eighteen million, six hundred fifty-five thousand, forty".