661261104000 has 2048 divisors, whose sum is σ = 3107040768000. Its totient is φ = 134568345600.

The previous prime is 661261103989. The next prime is 661261104013. The reversal of 661261104000 is 401162166.

661261104000 is a `hidden beast` number, since 6 + 6 + 1 + 2 + 611 + 0 + 40 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 976751662 + ... + 976752338.

It is an arithmetic number, because the mean of its divisors is an integer number (1517109750).

Almost surely, 2^661261104000 is an apocalyptic number.

661261104000 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 661261104000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1553520384000).

661261104000 is an abundant number, since it is smaller than the sum of its proper divisors (2445779664000).

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

661261104000 is a wasteful number, since it uses less digits than its factorization.

661261104000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758 (or 730 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

Adding to 661261104000 its reverse (401162166), we get a palindrome (661662266166).

The spelling of 661261104000 in words is "six hundred sixty-one billion, two hundred sixty-one million, one hundred four thousand".