2021821818421 has 2 divisors, whose sum is σ = 2021821818422. Its totient is φ = 2021821818420.

The previous prime is 2021821818403. The next prime is 2021821818433. The reversal of 2021821818421 is 1248181281202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1679514913521 + 342306904900 = 1295961^2 + 585070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2021821818421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2021821818461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010910909210 + 1010910909211.

It is an arithmetic number, because the mean of its divisors is an integer number (1010910909211).

Almost surely, 2^{2021821818421} is an apocalyptic number.

It is an amenable number.

2021821818421 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021821818421 is an equidigital number, since it uses as much as digits as its factorization.

2021821818421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32768, while the sum is 40.

The spelling of 2021821818421 in words is "two trillion, twenty-one billion, eight hundred twenty-one million, eight hundred eighteen thousand, four hundred twenty-one".