2665641561 has 16 divisors (see below), whose sum is σ = 3887282880. Its totient is φ = 1611379520.

The previous prime is 2665641553. The next prime is 2665641569. The reversal of 2665641561 is 1651465662.

It is an interprime number because it is at equal distance from previous prime (2665641553) and next prime (2665641569).

It is a cyclic number.

It is not a de Polignac number, because 2665641561 - 2³ = 2665641553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2665641569) 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, 90990 + ... + 116663.

It is an arithmetic number, because the mean of its divisors is an integer number (242955180).

Almost surely, 2^2665641561 is an apocalyptic number.

It is an amenable number.

2665641561 is a deficient number, since it is larger than the sum of its proper divisors (1221641319).

2665641561 is a wasteful number, since it uses less digits than its factorization.

2665641561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208056.

The product of its digits is 259200, while the sum is 42.

The square root of 2665641561 is about 51629.8514524301. The cubic root of 2665641561 is about 1386.5448337844.

The spelling of 2665641561 in words is "two billion, six hundred sixty-five million, six hundred forty-one thousand, five hundred sixty-one".