661165111500 has 96 divisors (see below), whose sum is σ = 1940473307136. Its totient is φ = 174922372800.

The previous prime is 661165111483. The next prime is 661165111507. The reversal of 661165111500 is 5111561166.

It is not an unprimeable number, because it can be changed into a prime (661165111507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1544842 + ... + 1925841.

It is an arithmetic number, because the mean of its divisors is an integer number (20213263616).

Almost surely, 2^661165111500 is an apocalyptic number.

661165111500 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661165111500 is an abundant number, since it is smaller than the sum of its proper divisors (1279308195636).

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

661165111500 is a wasteful number, since it uses less digits than its factorization.

661165111500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3470832 (or 3470820 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 33.

Adding to 661165111500 its reverse (5111561166), we get a palindrome (666276672666).

The spelling of 661165111500 in words is "six hundred sixty-one billion, one hundred sixty-five million, one hundred eleven thousand, five hundred".