2181420221 has 2 divisors, whose sum is σ = 2181420222. Its totient is φ = 2181420220.

The previous prime is 2181420217. The next prime is 2181420239. The reversal of 2181420221 is 1220241812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2137675225 + 43744996 = 46235^2 + 6614^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181420221 - 2² = 2181420217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2181420271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090710110 + 1090710111.

It is an arithmetic number, because the mean of its divisors is an integer number (1090710111).

Almost surely, 2^2181420221 is an apocalyptic number.

It is an amenable number.

2181420221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181420221 is an equidigital number, since it uses as much as digits as its factorization.

2181420221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 2181420221 is about 46705.6765393672. The cubic root of 2181420221 is about 1296.9197727426.

The spelling of 2181420221 in words is "two billion, one hundred eighty-one million, four hundred twenty thousand, two hundred twenty-one".