1665611613 has 16 divisors (see below), whose sum is σ = 2485589760. Its totient is φ = 1102300128.

The previous prime is 1665611609. The next prime is 1665611621. The reversal of 1665611613 is 3161165661.

It is not a de Polignac number, because 1665611613 - 2² = 1665611609 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665611513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 221445 + ... + 228842.

It is an arithmetic number, because the mean of its divisors is an integer number (155349360).

Almost surely, 2^1665611613 is an apocalyptic number.

It is an amenable number.

1665611613 is a deficient number, since it is larger than the sum of its proper divisors (819978147).

1665611613 is a wasteful number, since it uses less digits than its factorization.

1665611613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450433 (or 450427 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 1665611613 is about 40811.9052851003. The cubic root of 1665611613 is about 1185.3808677991.

It can be divided in two parts, 1665 and 611613, that added together give a triangular number (613278 = T₁₁₀₇).

The spelling of 1665611613 in words is "one billion, six hundred sixty-five million, six hundred eleven thousand, six hundred thirteen".