661353984000 has 1040 divisors, whose sum is σ = 2538132195456. Its totient is φ = 171196416000.

The previous prime is 661353983957. The next prime is 661353984001. The reversal of 661353984000 is 489353166.

661353984000 is a `hidden beast` number, since 66 + 13 + 539 + 8 + 40 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661353984001) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1534463785 + ... + 1534464215.

Almost surely, 2^661353984000 is an apocalyptic number.

661353984000 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 661353984000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1269066097728).

661353984000 is an abundant number, since it is smaller than the sum of its proper divisors (1876778211456).

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

661353984000 is an equidigital number, since it uses as much as digits as its factorization.

661353984000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 519 (or 478 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 45.

The spelling of 661353984000 in words is "six hundred sixty-one billion, three hundred fifty-three million, nine hundred eighty-four thousand".