21221201231 has 2 divisors, whose sum is σ = 21221201232. Its totient is φ = 21221201230.

The previous prime is 21221201191. The next prime is 21221201237. The reversal of 21221201231 is 13210212212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21221201231 - 2¹⁰ = 21221200207 is a prime.

It is a super-2 number, since 2×21221201231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221201237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610600615 + 10610600616.

It is an arithmetic number, because the mean of its divisors is an integer number (10610600616).

Almost surely, 2^21221201231 is an apocalyptic number.

21221201231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221201231 is an equidigital number, since it uses as much as digits as its factorization.

21221201231 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21221201231 its reverse (13210212212), we get a palindrome (34431413443).

The spelling of 21221201231 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, two hundred thirty-one".