2161640281 has 2 divisors, whose sum is σ = 2161640282. Its totient is φ = 2161640280.

The previous prime is 2161640269. The next prime is 2161640293. The reversal of 2161640281 is 1820461612.

It is a balanced prime because it is at equal distance from previous prime (2161640269) and next prime (2161640293).

It can be written as a sum of positive squares in only one way, i.e., 1394350281 + 767290000 = 37341^2 + 27700^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161640281 - 2³¹ = 14156633 is a prime.

It is a super-2 number, since 2×2161640281² = 9345377408883517922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2161640081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080820140 + 1080820141.

It is an arithmetic number, because the mean of its divisors is an integer number (1080820141).

Almost surely, 2^2161640281 is an apocalyptic number.

2161640281 is the 20793-rd centered decagonal number.

It is an amenable number.

2161640281 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161640281 is an equidigital number, since it uses as much as digits as its factorization.

2161640281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 2161640281 is about 46493.4434194758. The cubic root of 2161640281 is about 1292.9879421798.

The spelling of 2161640281 in words is "two billion, one hundred sixty-one million, six hundred forty thousand, two hundred eighty-one".