999631 has 2 divisors, whose sum is σ = 999632. Its totient is φ = 999630.

The previous prime is 999623. The next prime is 999653. The reversal of 999631 is 136999.

It is a weak prime.

It is an emirp because it is prime and its reverse (136999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999631 - 2³ = 999623 is a prime.

It is a super-2 number, since 2×999631² = 1998524272322, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499815 + 499816.

It is an arithmetic number, because the mean of its divisors is an integer number (499816).

2⁹⁹⁹⁶³¹ is an apocalyptic number.

999631 is a deficient number, since it is larger than the sum of its proper divisors (1).

999631 is an equidigital number, since it uses as much as digits as its factorization.

999631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13122, while the sum is 37.

The square root of 999631 is about 999.8154829767. The cubic root of 999631 is about 99.9876984868.

It can be divided in two parts, 99 and 9631, that added together give a triangular number (9730 = T₁₃₉).

The spelling of 999631 in words is "nine hundred ninety-nine thousand, six hundred thirty-one".