21311220212321 has 4 divisors (see below), whose sum is σ = 22950544844052. Its totient is φ = 19671895580592.

The previous prime is 21311220212279. The next prime is 21311220212333. The reversal of 21311220212321 is 12321202211312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3844579777600 + 17466640434721 = 1960760^2 + 4179311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311220212321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311220212621) 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, 819662315846 + ... + 819662315871.

It is an arithmetic number, because the mean of its divisors is an integer number (5737636211013).

Almost surely, 2^{21311220212321} is an apocalyptic number.

It is an amenable number.

21311220212321 is a deficient number, since it is larger than the sum of its proper divisors (1639324631731).

21311220212321 is a wasteful number, since it uses less digits than its factorization.

21311220212321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639324631730.

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 21311220212321 its reverse (12321202211312), we get a palindrome (33632422423633).

The spelling of 21311220212321 in words is "twenty-one trillion, three hundred eleven billion, two hundred twenty million, two hundred twelve thousand, three hundred twenty-one".