2661335981 has 2 divisors, whose sum is σ = 2661335982. Its totient is φ = 2661335980.

The previous prime is 2661335959. The next prime is 2661336017. The reversal of 2661335981 is 1895331662.

2661335981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2409828100 + 251507881 = 49090^2 + 15859^2 .

It is a cyclic number.

It is not a de Polignac number, because 2661335981 - 2⁶ = 2661335917 is a prime.

It is a super-2 number, since 2×2661335981² = 14165418407530464722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2661335921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330667990 + 1330667991.

It is an arithmetic number, because the mean of its divisors is an integer number (1330667991).

Almost surely, 2^2661335981 is an apocalyptic number.

It is an amenable number.

2661335981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661335981 is an equidigital number, since it uses as much as digits as its factorization.

2661335981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 44.

The square root of 2661335981 is about 51588.1379873319. The cubic root of 2661335981 is about 1385.7979095555.

The spelling of 2661335981 in words is "two billion, six hundred sixty-one million, three hundred thirty-five thousand, nine hundred eighty-one".