21012001121 has 2 divisors, whose sum is σ = 21012001122. Its totient is φ = 21012001120.

The previous prime is 21012001111. The next prime is 21012001163. The reversal of 21012001121 is 12110021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20741760400 + 270240721 = 144020^2 + 16439^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012001121 - 2³⁴ = 3832131937 is a prime.

It is a super-2 number, since 2×21012001121² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21012001111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506000560 + 10506000561.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000561).

Almost surely, 2^21012001121 is an apocalyptic number.

It is an amenable number.

21012001121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001121 is an equidigital number, since it uses as much as digits as its factorization.

21012001121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21012001121 its reverse (12110021012), we get a palindrome (33122022133).

The spelling of 21012001121 in words is "twenty-one billion, twelve million, one thousand, one hundred twenty-one".