1656005665 has 4 divisors (see below), whose sum is σ = 1987206804. Its totient is φ = 1324804528.

The previous prime is 1656005653. The next prime is 1656005671. The reversal of 1656005665 is 5665006561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5665006561 = 45641 ⋅124121.

It can be written as a sum of positive squares in 2 ways, for example, as 727219089 + 928786576 = 26967^2 + 30476^2 .

It is a cyclic number.

It is not a de Polignac number, because 1656005665 - 2¹⁵ = 1655972897 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165600562 + ... + 165600571.

It is an arithmetic number, because the mean of its divisors is an integer number (496801701).

Almost surely, 2^1656005665 is an apocalyptic number.

It is an amenable number.

1656005665 is a deficient number, since it is larger than the sum of its proper divisors (331201139).

1656005665 is an equidigital number, since it uses as much as digits as its factorization.

1656005665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331201138.

The product of its (nonzero) digits is 162000, while the sum is 40.

The square root of 1656005665 is about 40694.0495035822. The cubic root of 1656005665 is about 1183.0976890209.

The spelling of 1656005665 in words is "one billion, six hundred fifty-six million, five thousand, six hundred sixty-five".