661189899202560 has 4160 divisors, whose sum is σ = 3053465513683200. Its totient is φ = 133101439156224.

The previous prime is 661189899202543. The next prime is 661189899202607. The reversal of 661189899202560 is 65202998981166.

It is a tau number, because it is divible by the number of its divisors (4160).

It is a hoax number, since the sum of its digits (72) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 389622803632 + ... + 389622805328.

Almost surely, 2^{661189899202560} is an apocalyptic number.

661189899202560 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 661189899202560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1526732756841600).

661189899202560 is an abundant number, since it is smaller than the sum of its proper divisors (2392275614480640).

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

661189899202560 is a wasteful number, since it uses less digits than its factorization.

661189899202560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1876 (or 1845 counting only the distinct ones).

The product of its (nonzero) digits is 201553920, while the sum is 72.

The spelling of 661189899202560 in words is "six hundred sixty-one trillion, one hundred eighty-nine billion, eight hundred ninety-nine million, two hundred two thousand, five hundred sixty".