2161660566 has 128 divisors (see below), whose sum is σ = 5127929856. Its totient is φ = 601856640.

The previous prime is 2161660559. The next prime is 2161660601. The reversal of 2161660566 is 6650661612.

It is a super-3 number, since 3×2161660566³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2613445 + ... + 2614271.

It is an arithmetic number, because the mean of its divisors is an integer number (40061952).

Almost surely, 2^2161660566 is an apocalyptic number.

2161660566 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 2161660566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2563964928).

2161660566 is an abundant number, since it is smaller than the sum of its proper divisors (2966269290).

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

2161660566 is a wasteful number, since it uses less digits than its factorization.

2161660566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 946.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 2161660566 is about 46493.6615680030. The cubic root of 2161660566 is about 1292.9919866668.

The spelling of 2161660566 in words is "two billion, one hundred sixty-one million, six hundred sixty thousand, five hundred sixty-six".