2661661664 has 72 divisors (see below), whose sum is σ = 5582137680. Its totient is φ = 1249016832.

The previous prime is 2661661609. The next prime is 2661661669. The reversal of 2661661664 is 4661661662.

It is a super-3 number, since 3×2661661664³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2661661669) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1304357 + ... + 1306395.

It is an arithmetic number, because the mean of its divisors is an integer number (77529690).

Almost surely, 2^2661661664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2661661664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2791068840).

2661661664 is an abundant number, since it is smaller than the sum of its proper divisors (2920476016).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2661661664 is a wasteful number, since it uses less digits than its factorization.

2661661664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2200 (or 2173 counting only the distinct ones).

The product of its digits is 373248, while the sum is 44.

The square root of 2661661664 is about 51591.2944594338. The cubic root of 2661661664 is about 1385.8544366048.

The spelling of 2661661664 in words is "two billion, six hundred sixty-one million, six hundred sixty-one thousand, six hundred sixty-four".