214821781 has 2 divisors, whose sum is σ = 214821782. Its totient is φ = 214821780.

The previous prime is 214821779. The next prime is 214821787. The reversal of 214821781 is 187128412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 202606756 + 12215025 = 14234^2 + 3495^2 .

It is a cyclic number.

It is not a de Polignac number, because 214821781 - 2¹ = 214821779 is a prime.

It is a super-2 number, since 2×214821781² = 92296795184023922, which contains 22 as substring.

Together with 214821779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (214821787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107410890 + 107410891.

It is an arithmetic number, because the mean of its divisors is an integer number (107410891).

Almost surely, 2^214821781 is an apocalyptic number.

It is an amenable number.

214821781 is a deficient number, since it is larger than the sum of its proper divisors (1).

214821781 is an equidigital number, since it uses as much as digits as its factorization.

214821781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7168, while the sum is 34.

The square root of 214821781 is about 14656.7998212434. The cubic root of 214821781 is about 598.9070668522.

The spelling of 214821781 in words is "two hundred fourteen million, eight hundred twenty-one thousand, seven hundred eighty-one".