2016665261 has 4 divisors (see below), whose sum is σ = 2171793372. Its totient is φ = 1861537152.

The previous prime is 2016665251. The next prime is 2016665267. The reversal of 2016665261 is 1625666102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 949009636 + 1067655625 = 30806^2 + 32675^2 .

It is a cyclic number.

It is not a de Polignac number, because 2016665261 - 2²⁶ = 1949556397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2016665267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77564036 + ... + 77564061.

It is an arithmetic number, because the mean of its divisors is an integer number (542948343).

Almost surely, 2^2016665261 is an apocalyptic number.

It is an amenable number.

2016665261 is a deficient number, since it is larger than the sum of its proper divisors (155128111).

2016665261 is a wasteful number, since it uses less digits than its factorization.

2016665261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155128110.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 2016665261 is about 44907.2963002673. The cubic root of 2016665261 is about 1263.4108601919.

The spelling of 2016665261 in words is "two billion, sixteen million, six hundred sixty-five thousand, two hundred sixty-one".