999728381 has 2 divisors, whose sum is σ = 999728382. Its totient is φ = 999728380.

The previous prime is 999728321. The next prime is 999728413. The reversal of 999728381 is 183827999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 857904100 + 141824281 = 29290^2 + 11909^2 .

It is an emirp because it is prime and its reverse (183827999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999728381 - 2²⁶ = 932619517 is a prime.

It is a super-2 number, since 2×999728381² = 1998913671553762322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999728321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499864190 + 499864191.

It is an arithmetic number, because the mean of its divisors is an integer number (499864191).

Almost surely, 2^999728381 is an apocalyptic number.

It is an amenable number.

999728381 is a deficient number, since it is larger than the sum of its proper divisors (1).

999728381 is an equidigital number, since it uses as much as digits as its factorization.

999728381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1959552, while the sum is 56.

The square root of 999728381 is about 31618.4816365366. The cubic root of 999728381 is about 999.9094521347.

The spelling of 999728381 in words is "nine hundred ninety-nine million, seven hundred twenty-eight thousand, three hundred eighty-one".