21309381371 has 6 divisors (see below), whose sum is σ = 21772421340. Its totient is φ = 20855988116.

The previous prime is 21309381367. The next prime is 21309381413. The reversal of 21309381371 is 17318390312.

It is not a de Polignac number, because 21309381371 - 2² = 21309381367 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21309381671) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4821101 + ... + 4825518.

It is an arithmetic number, because the mean of its divisors is an integer number (3628736890).

Almost surely, 2^21309381371 is an apocalyptic number.

21309381371 is a deficient number, since it is larger than the sum of its proper divisors (463039969).

21309381371 is an frugal number, since it uses more digits than its factorization.

21309381371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9646713 (or 9646666 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 38.

The spelling of 21309381371 in words is "twenty-one billion, three hundred nine million, three hundred eighty-one thousand, three hundred seventy-one".