21131210999 has 4 divisors (see below), whose sum is σ = 21174602064. Its totient is φ = 21087819936.

The previous prime is 21131210983. The next prime is 21131211047. The reversal of 21131210999 is 99901213112.

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

It is a cyclic number.

It is not a de Polignac number, because 21131210999 - 2⁴ = 21131210983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131210299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21694802 + ... + 21695775.

It is an arithmetic number, because the mean of its divisors is an integer number (5293650516).

Almost surely, 2^21131210999 is an apocalyptic number.

21131210999 is a deficient number, since it is larger than the sum of its proper divisors (43391065).

21131210999 is an equidigital number, since it uses as much as digits as its factorization.

21131210999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43391064.

The product of its (nonzero) digits is 8748, while the sum is 38.

The spelling of 21131210999 in words is "twenty-one billion, one hundred thirty-one million, two hundred ten thousand, nine hundred ninety-nine".