661204593911520 has 960 divisors, whose sum is σ = 2478928330682496. Its totient is φ = 165618571345920.

The previous prime is 661204593911473. The next prime is 661204593911531. The reversal of 661204593911520 is 25119395402166.

It is a happy number.

661204593911520 is a `hidden beast` number, since 6 + 6 + 1 + 2 + 0 + 459 + 39 + 1 + 152 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 11218807492 + ... + 11218866428.

Almost surely, 2^{661204593911520} is an apocalyptic number.

661204593911520 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 661204593911520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1239464165341248).

661204593911520 is an abundant number, since it is smaller than the sum of its proper divisors (1817723736770976).

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

661204593911520 is a wasteful number, since it uses less digits than its factorization.

661204593911520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59665 (or 59648 counting only the distinct ones).

The product of its (nonzero) digits is 3499200, while the sum is 54.

The spelling of 661204593911520 in words is "six hundred sixty-one trillion, two hundred four billion, five hundred ninety-three million, nine hundred eleven thousand, five hundred twenty".