21309671231 has 4 divisors (see below), whose sum is σ = 21309988200. Its totient is φ = 21309354264.

The previous prime is 21309671213. The next prime is 21309671233. The reversal of 21309671231 is 13217690312.

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 21309671231 - 2¹⁸ = 21309409087 is a prime.

It is a super-2 number, since 2×21309671231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21309671191 and 21309671200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309671233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13316 + ... + 206873.

It is an arithmetic number, because the mean of its divisors is an integer number (5327497050).

Almost surely, 2^21309671231 is an apocalyptic number.

21309671231 is a deficient number, since it is larger than the sum of its proper divisors (316969).

21309671231 is an equidigital number, since it uses as much as digits as its factorization.

21309671231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316968.

The product of its (nonzero) digits is 13608, while the sum is 35.

The spelling of 21309671231 in words is "twenty-one billion, three hundred nine million, six hundred seventy-one thousand, two hundred thirty-one".