661551160000 has 140 divisors (see below), whose sum is σ = 1693352203840. Its totient is φ = 256083840000.

The previous prime is 661551159977. The next prime is 661551160001. The reversal of 661551160000 is 61155166.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (661551160001) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 973246 + ... + 1506754.

Almost surely, 2^661551160000 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 661551160000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (846676101920).

661551160000 is an abundant number, since it is smaller than the sum of its proper divisors (1031801043840).

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

661551160000 is an equidigital number, since it uses as much as digits as its factorization.

661551160000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533572 (or 533547 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 31.

The spelling of 661551160000 in words is "six hundred sixty-one billion, five hundred fifty-one million, one hundred sixty thousand".