1665871061 has 4 divisors (see below), whose sum is σ = 1665997824. Its totient is φ = 1665744300.

The previous prime is 1665871057. The next prime is 1665871079. The reversal of 1665871061 is 1601785661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1601785661 = 7 ⋅228826523.

It is a cyclic number.

It is not a de Polignac number, because 1665871061 - 2² = 1665871057 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665871261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41045 + ... + 70826.

It is an arithmetic number, because the mean of its divisors is an integer number (416499456).

Almost surely, 2^1665871061 is an apocalyptic number.

It is an amenable number.

1665871061 is a deficient number, since it is larger than the sum of its proper divisors (126763).

1665871061 is a wasteful number, since it uses less digits than its factorization.

1665871061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126762.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 1665871061 is about 40815.0837436358. The cubic root of 1665871061 is about 1185.4424125045.

The spelling of 1665871061 in words is "one billion, six hundred sixty-five million, eight hundred seventy-one thousand, sixty-one".