661066715550 has 24 divisors (see below), whose sum is σ = 1639445454936. Its totient is φ = 176284457440.

The previous prime is 661066715537. The next prime is 661066715567. The reversal of 661066715550 is 55517660166.

It is a super-2 number, since 2×661066715550² (a number of 24 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 661066715550.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2203555569 + ... + 2203555868.

It is an arithmetic number, because the mean of its divisors is an integer number (68310227289).

Almost surely, 2^661066715550 is an apocalyptic number.

661066715550 is an abundant number, since it is smaller than the sum of its proper divisors (978378739386).

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

661066715550 is a wasteful number, since it uses less digits than its factorization.

661066715550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4407111452 (or 4407111447 counting only the distinct ones).

The product of its (nonzero) digits is 1134000, while the sum is 48.

The spelling of 661066715550 in words is "six hundred sixty-one billion, sixty-six million, seven hundred fifteen thousand, five hundred fifty".