999976381 has 2 divisors, whose sum is σ = 999976382. Its totient is φ = 999976380.

The previous prime is 999976379. The next prime is 999976423. The reversal of 999976381 is 183679999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 986588100 + 13388281 = 31410^2 + 3659^2 .

It is an emirp because it is prime and its reverse (183679999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999976381 - 2¹ = 999976379 is a prime.

It is a super-2 number, since 2×999976381² = 1999905525115714322, which contains 22 as substring.

Together with 999976379, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999976181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499988190 + 499988191.

It is an arithmetic number, because the mean of its divisors is an integer number (499988191).

Almost surely, 2^999976381 is an apocalyptic number.

It is an amenable number.

999976381 is a deficient number, since it is larger than the sum of its proper divisors (1).

999976381 is an equidigital number, since it uses as much as digits as its factorization.

999976381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6613488, while the sum is 61.

The square root of 999976381 is about 31622.4031502984. The cubic root of 999976381 is about 999.9921269380.

The spelling of 999976381 in words is "nine hundred ninety-nine million, nine hundred seventy-six thousand, three hundred eighty-one".