1661506611075 has 36 divisors (see below), whose sum is σ = 2979568061808. Its totient is φ = 885057422400.

The previous prime is 1661506611053. The next prime is 1661506611109. The reversal of 1661506611075 is 5701166051661.

1661506611075 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 506 + 61 + 10 + 75 = 666.

It is not a de Polignac number, because 1661506611075 - 2¹¹ = 1661506609027 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1661506611075.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 4312519 + ... + 4681968.

Almost surely, 2^{1661506611075} is an apocalyptic number.

1661506611075 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1661506611075 is a deficient number, since it is larger than the sum of its proper divisors (1318061450733).

1661506611075 is a wasteful number, since it uses less digits than its factorization.

1661506611075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8995324 (or 8995316 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 45.

The spelling of 1661506611075 in words is "one trillion, six hundred sixty-one billion, five hundred six million, six hundred eleven thousand, seventy-five".