210891009 has 32 divisors (see below), whose sum is σ = 335051776. Its totient is φ = 115473600.

The previous prime is 210891007. The next prime is 210891017. The reversal of 210891009 is 900198012.

It is not a de Polignac number, because 210891009 - 2¹ = 210891007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (210891007) 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 in 31 ways as a sum of consecutive naturals, for example, 50034 + ... + 54084.

It is an arithmetic number, because the mean of its divisors is an integer number (10470368).

Almost surely, 2^210891009 is an apocalyptic number.

It is an amenable number.

210891009 is a deficient number, since it is larger than the sum of its proper divisors (124160767).

210891009 is a wasteful number, since it uses less digits than its factorization.

210891009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4165.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 210891009 is about 14522.0869368008. The cubic root of 210891009 is about 595.2316580230.

The spelling of 210891009 in words is "two hundred ten million, eight hundred ninety-one thousand, nine".