21201121231 has 2 divisors, whose sum is σ = 21201121232. Its totient is φ = 21201121230.

The previous prime is 21201121229. The next prime is 21201121241. The reversal of 21201121231 is 13212110212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21201121231 - 2¹ = 21201121229 is a prime.

It is a super-2 number, since 2×21201121231² (a number of 21 digits) contains 22 as substring.

Together with 21201121229, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201121241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600560615 + 10600560616.

It is an arithmetic number, because the mean of its divisors is an integer number (10600560616).

Almost surely, 2^21201121231 is an apocalyptic number.

21201121231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201121231 is an equidigital number, since it uses as much as digits as its factorization.

21201121231 is an evil number, because the sum of its binary digits is even.

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

Adding to 21201121231 its reverse (13212110212), we get a palindrome (34413231443).

The spelling of 21201121231 in words is "twenty-one billion, two hundred one million, one hundred twenty-one thousand, two hundred thirty-one".