102212821 has 2 divisors, whose sum is σ = 102212822. Its totient is φ = 102212820.

The previous prime is 102212819. The next prime is 102212843. The reversal of 102212821 is 128212201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 92910321 + 9302500 = 9639^2 + 3050^2 .

It is a cyclic number.

It is not a de Polignac number, because 102212821 - 2¹ = 102212819 is a prime.

Together with 102212819, 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 (102212801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51106410 + 51106411.

It is an arithmetic number, because the mean of its divisors is an integer number (51106411).

Almost surely, 2^102212821 is an apocalyptic number.

It is an amenable number.

102212821 is a deficient number, since it is larger than the sum of its proper divisors (1).

102212821 is an equidigital number, since it uses as much as digits as its factorization.

102212821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 102212821 is about 10110.0356577017. The cubic root of 102212821 is about 467.5576045006.

The spelling of 102212821 in words is "one hundred two million, two hundred twelve thousand, eight hundred twenty-one".