21011212321 has 4 divisors (see below), whose sum is σ = 22921322544. Its totient is φ = 19101102100.

The previous prime is 21011212297. The next prime is 21011212331. The reversal of 21011212321 is 12321211012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21011212321 - 2⁷ = 21011212193 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011212295 and 21011212304.

It is not an unprimeable number, because it can be changed into a prime (21011212331) 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, 955055095 + ... + 955055116.

It is an arithmetic number, because the mean of its divisors is an integer number (5730330636).

Almost surely, 2^21011212321 is an apocalyptic number.

It is an amenable number.

21011212321 is a deficient number, since it is larger than the sum of its proper divisors (1910110223).

21011212321 is a wasteful number, since it uses less digits than its factorization.

21011212321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1910110222.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21011212321 its reverse (12321211012), we get a palindrome (33332423333).

It can be divided in two parts, 21011 and 212321, that added together give a palindrome (233332).

The spelling of 21011212321 in words is "twenty-one billion, eleven million, two hundred twelve thousand, three hundred twenty-one".