1661571755 has 16 divisors (see below), whose sum is σ = 2222290080. Its totient is φ = 1185219072.

The previous prime is 1661571707. The next prime is 1661571763. The reversal of 1661571755 is 5571751661.

It is a cyclic number.

It is not a de Polignac number, because 1661571755 - 2²⁸ = 1393136299 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 512804 + ... + 516033.

It is an arithmetic number, because the mean of its divisors is an integer number (138893130).

Almost surely, 2^1661571755 is an apocalyptic number.

1661571755 is a deficient number, since it is larger than the sum of its proper divisors (560718325).

1661571755 is a wasteful number, since it uses less digits than its factorization.

1661571755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1028878.

The product of its digits is 220500, while the sum is 44.

The square root of 1661571755 is about 40762.3816158968. The cubic root of 1661571755 is about 1184.4217311850.

The spelling of 1661571755 in words is "one billion, six hundred sixty-one million, five hundred seventy-one thousand, seven hundred fifty-five".