999903661 has 4 divisors (see below), whose sum is σ = 1002092092. Its totient is φ = 997715232.

The previous prime is 999903659. The next prime is 999903677. The reversal of 999903661 is 166309999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 691374436 + 308529225 = 26294^2 + 17565^2 .

It is a cyclic number.

It is not a de Polignac number, because 999903661 - 2¹ = 999903659 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 999903599 and 999903608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999903631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093530 + ... + 1094443.

It is an arithmetic number, because the mean of its divisors is an integer number (250523023).

Almost surely, 2^999903661 is an apocalyptic number.

It is an amenable number.

999903661 is a deficient number, since it is larger than the sum of its proper divisors (2188431).

999903661 is a wasteful number, since it uses less digits than its factorization.

999903661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2188430.

The product of its (nonzero) digits is 708588, while the sum is 52.

The square root of 999903661 is about 31621.2533116573. The cubic root of 999903661 is about 999.9678859687.

The spelling of 999903661 in words is "nine hundred ninety-nine million, nine hundred three thousand, six hundred sixty-one".