2181382661 has 2 divisors, whose sum is σ = 2181382662. Its totient is φ = 2181382660.

The previous prime is 2181382627. The next prime is 2181382699. The reversal of 2181382661 is 1662831812.

It is an a-pointer prime, because the next prime (2181382699) can be obtained adding 2181382661 to its sum of digits (38).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1408876225 + 772506436 = 37535^2 + 27794^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181382661 - 2⁶ = 2181382597 is a prime.

It is a super-2 number, since 2×2181382661² = 9516860627422881842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2181382361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090691330 + 1090691331.

It is an arithmetic number, because the mean of its divisors is an integer number (1090691331).

Almost surely, 2^2181382661 is an apocalyptic number.

It is an amenable number.

2181382661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181382661 is an equidigital number, since it uses as much as digits as its factorization.

2181382661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 38.

The square root of 2181382661 is about 46705.2744451845. The cubic root of 2181382661 is about 1296.9123291842.

The spelling of 2181382661 in words is "two billion, one hundred eighty-one million, three hundred eighty-two thousand, six hundred sixty-one".