661752171215646 has 16 divisors (see below), whose sum is σ = 1512576391350144. Its totient is φ = 189072048918744.

The previous prime is 661752171215581. The next prime is 661752171215659. The reversal of 661752171215646 is 646512171257166.

It is a happy number.

It is a super-2 number, since 2×661752171215646² (a number of 30 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661752171215646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7878002038240 + ... + 7878002038323.

It is an arithmetic number, because the mean of its divisors is an integer number (94536024459384).

Almost surely, 2^{661752171215646} is an apocalyptic number.

661752171215646 is an abundant number, since it is smaller than the sum of its proper divisors (850824220134498).

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

661752171215646 is a wasteful number, since it uses less digits than its factorization.

661752171215646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15756004076575.

The product of its digits is 25401600, while the sum is 60.

The spelling of 661752171215646 in words is "six hundred sixty-one trillion, seven hundred fifty-two billion, one hundred seventy-one million, two hundred fifteen thousand, six hundred forty-six".