816121 has 2 divisors, whose sum is σ = 816122. Its totient is φ = 816120.

The previous prime is 816113. The next prime is 816131. The reversal of 816121 is 121618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 622521 + 193600 = 789^2 + 440^2 .

It is a cyclic number.

It is not a de Polignac number, because 816121 - 2³ = 816113 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (816131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408060 + 408061.

It is an arithmetic number, because the mean of its divisors is an integer number (408061).

2⁸¹⁶¹²¹ is an apocalyptic number.

It is an amenable number.

816121 is a deficient number, since it is larger than the sum of its proper divisors (1).

816121 is an equidigital number, since it uses as much as digits as its factorization.

816121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96, while the sum is 19.

The square root of 816121 is about 903.3941553940. The cubic root of 816121 is about 93.4511932259.

Adding to 816121 its reverse (121618), we get a palindrome (937739).

It can be divided in two parts, 8 and 16121, that added together give a square (16129 = 127²).

The spelling of 816121 in words is "eight hundred sixteen thousand, one hundred twenty-one".