900991 has 8 divisors (see below), whose sum is σ = 1109024. Its totient is φ = 712800.

The previous prime is 900973. The next prime is 900997. The reversal of 900991 is 199009.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 900991 - 2⁵ = 900959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (900997) 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 7 ways as a sum of consecutive naturals, for example, 4860 + ... + 5041.

It is an arithmetic number, because the mean of its divisors is an integer number (138628).

2⁹⁰⁰⁹⁹¹ is an apocalyptic number.

900991 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

900991 is a deficient number, since it is larger than the sum of its proper divisors (208033).

900991 is a wasteful number, since it uses less digits than its factorization.

900991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9921.

The product of its (nonzero) digits is 729, while the sum is 28.

The square root of 900991 is about 949.2054572115. The cubic root of 900991 is about 96.5843624981.

It can be divided in two parts, 90099 and 1, that added together give a triangular number (90100 = T₄₂₄).

The spelling of 900991 in words is "nine hundred thousand, nine hundred ninety-one".