21312202121 has 16 divisors (see below), whose sum is σ = 25198617600. Its totient is φ = 17638871040.

The previous prime is 21312202081. The next prime is 21312202129. The reversal of 21312202121 is 12120221312.

It is not a de Polignac number, because 21312202121 - 2²² = 21308007817 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 21312202121.

It is not an unprimeable number, because it can be changed into a prime (21312202129) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11936 + ... + 206801.

It is an arithmetic number, because the mean of its divisors is an integer number (1574913600).

Almost surely, 2^21312202121 is an apocalyptic number.

It is an amenable number.

21312202121 is a deficient number, since it is larger than the sum of its proper divisors (3886415479).

21312202121 is a wasteful number, since it uses less digits than its factorization.

21312202121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219224.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21312202121 its reverse (12120221312), we get a palindrome (33432423433).

The spelling of 21312202121 in words is "twenty-one billion, three hundred twelve million, two hundred two thousand, one hundred twenty-one".