21212021801 has 2 divisors, whose sum is σ = 21212021802. Its totient is φ = 21212021800.

The previous prime is 21212021773. The next prime is 21212021821. The reversal of 21212021801 is 10812021212.

It is an a-pointer prime, because the next prime (21212021821) can be obtained adding 21212021801 to its sum of digits (20).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20491636201 + 720385600 = 143149^2 + 26840^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212021801 is a prime.

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 (21212021821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606010900 + 10606010901.

It is an arithmetic number, because the mean of its divisors is an integer number (10606010901).

Almost surely, 2^21212021801 is an apocalyptic number.

It is an amenable number.

21212021801 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212021801 is an equidigital number, since it uses as much as digits as its factorization.

21212021801 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 20.

The spelling of 21212021801 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, eight hundred one".