21012232121 has 2 divisors, whose sum is σ = 21012232122. Its totient is φ = 21012232120.

The previous prime is 21012232063. The next prime is 21012232127. The reversal of 21012232121 is 12123221012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17641152400 + 3371079721 = 132820^2 + 58061^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012232121 - 2⁶ = 21012232057 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21012232121.

It is not a weakly prime, because it can be changed into another prime (21012232127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506116060 + 10506116061.

It is an arithmetic number, because the mean of its divisors is an integer number (10506116061).

Almost surely, 2^21012232121 is an apocalyptic number.

It is an amenable number.

21012232121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012232121 is an equidigital number, since it uses as much as digits as its factorization.

21012232121 is an evil number, because the sum of its binary digits is even.

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

Adding to 21012232121 its reverse (12123221012), we get a palindrome (33135453133).

The spelling of 21012232121 in words is "twenty-one billion, twelve million, two hundred thirty-two thousand, one hundred twenty-one".