1836161221 has 2 divisors, whose sum is σ = 1836161222. Its totient is φ = 1836161220.

The previous prime is 1836161207. The next prime is 1836161281. The reversal of 1836161221 is 1221616381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1483097121 + 353064100 = 38511^2 + 18790^2 .

It is a cyclic number.

It is not a de Polignac number, because 1836161221 - 2²⁵ = 1802606789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1836161281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 918080610 + 918080611.

It is an arithmetic number, because the mean of its divisors is an integer number (918080611).

Almost surely, 2^1836161221 is an apocalyptic number.

It is an amenable number.

1836161221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1836161221 is an equidigital number, since it uses as much as digits as its factorization.

1836161221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 31.

The square root of 1836161221 is about 42850.4518179214. The cubic root of 1836161221 is about 1224.5323709487.

The spelling of 1836161221 in words is "one billion, eight hundred thirty-six million, one hundred sixty-one thousand, two hundred twenty-one".