21212120201 has 4 divisors (see below), whose sum is σ = 22328547600. Its totient is φ = 20095692804.

The previous prime is 21212120183. The next prime is 21212120257. The reversal of 21212120201 is 10202121212.

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 a de Polignac number, because none of the positive numbers 2^k-21212120201 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21212120261) 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, 558213671 + ... + 558213708.

It is an arithmetic number, because the mean of its divisors is an integer number (5582136900).

Almost surely, 2^21212120201 is an apocalyptic number.

It is an amenable number.

21212120201 is a deficient number, since it is larger than the sum of its proper divisors (1116427399).

21212120201 is a wasteful number, since it uses less digits than its factorization.

21212120201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1116427398.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21212120201 its reverse (10202121212), we get a palindrome (31414241413).

The spelling of 21212120201 in words is "twenty-one billion, two hundred twelve million, one hundred twenty thousand, two hundred one".