999381 has 16 divisors (see below), whose sum is σ = 1425600. Its totient is φ = 620928.

The previous prime is 999377. The next prime is 999389. The reversal of 999381 is 183999.

It is not a de Polignac number, because 999381 - 2² = 999377 is a prime.

It is a super-2 number, since 2×999381² = 1997524766322, which contains 22 as substring.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 999381.

It is not an unprimeable number, because it can be changed into a prime (999389) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4975 + ... + 5171.

It is an arithmetic number, because the mean of its divisors is an integer number (89100).

2⁹⁹⁹³⁸¹ is an apocalyptic number.

It is an amenable number.

999381 is a deficient number, since it is larger than the sum of its proper divisors (426219).

999381 is a wasteful number, since it uses less digits than its factorization.

999381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308.

The product of its digits is 17496, while the sum is 39.

The square root of 999381 is about 999.6904520900. The cubic root of 999381 is about 99.9793624079.

The spelling of 999381 in words is "nine hundred ninety-nine thousand, three hundred eighty-one".