999821261 has 2 divisors, whose sum is σ = 999821262. Its totient is φ = 999821260.

The previous prime is 999821243. The next prime is 999821279. The reversal of 999821261 is 162128999.

It is a balanced prime because it is at equal distance from previous prime (999821243) and next prime (999821279).

It can be written as a sum of positive squares in only one way, i.e., 719258761 + 280562500 = 26819^2 + 16750^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999821261 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p_50838887 and since 999821261 and 50838887 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999821231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499910630 + 499910631.

It is an arithmetic number, because the mean of its divisors is an integer number (499910631).

Almost surely, 2^999821261 is an apocalyptic number.

It is an amenable number.

999821261 is a deficient number, since it is larger than the sum of its proper divisors (1).

999821261 is an equidigital number, since it uses as much as digits as its factorization.

999821261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 47.

The square root of 999821261 is about 31619.9503636549. The cubic root of 999821261 is about 999.9404167832.

The spelling of 999821261 in words is "nine hundred ninety-nine million, eight hundred twenty-one thousand, two hundred sixty-one".