21311021323 has 4 divisors (see below), whose sum is σ = 21342224088. Its totient is φ = 21279818560.

The previous prime is 21311021293. The next prime is 21311021341. The reversal of 21311021323 is 32312011312.

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 21311021323 - 2³³ = 12721086731 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21311021323.

It is not an unprimeable number, because it can be changed into a prime (21311021383) 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 3 ways as a sum of consecutive naturals, for example, 15600358 + ... + 15601723.

It is an arithmetic number, because the mean of its divisors is an integer number (5335556022).

Almost surely, 2^21311021323 is an apocalyptic number.

21311021323 is a deficient number, since it is larger than the sum of its proper divisors (31202765).

21311021323 is an equidigital number, since it uses as much as digits as its factorization.

21311021323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31202764.

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 21311021323 its reverse (32312011312), we get a palindrome (53623032635).

The spelling of 21311021323 in words is "twenty-one billion, three hundred eleven million, twenty-one thousand, three hundred twenty-three".