999990805 has 16 divisors (see below), whose sum is σ = 1377979200. Its totient is φ = 688988160.

The previous prime is 999990787. The next prime is 999990809. The reversal of 999990805 is 508099999.

It is not a de Polignac number, because 999990805 - 2⁹ = 999990293 is a prime.

It is a super-2 number, since 2×999990805² = 1999963220169096050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 999990805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999990809) 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, 477420 + ... + 479509.

It is an arithmetic number, because the mean of its divisors is an integer number (86123700).

Almost surely, 2^999990805 is an apocalyptic number.

999990805 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

It is an amenable number.

999990805 is a deficient number, since it is larger than the sum of its proper divisors (377988395).

999990805 is a wasteful number, since it uses less digits than its factorization.

999990805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 956964.

The product of its (nonzero) digits is 2361960, while the sum is 58.

The square root of 999990805 is about 31622.6312156342. The cubic root of 999990805 is about 999.9969349906.

The spelling of 999990805 in words is "nine hundred ninety-nine million, nine hundred ninety thousand, eight hundred five".