217025021 has 2 divisors, whose sum is σ = 217025022. Its totient is φ = 217025020.

The previous prime is 217024981. The next prime is 217025023. The reversal of 217025021 is 120520712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 144264121 + 72760900 = 12011^2 + 8530^2 .

It is a cyclic number.

It is not a de Polignac number, because 217025021 - 2¹⁸ = 216762877 is a prime.

Together with 217025023, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 217024984 and 217025002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217025023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108512510 + 108512511.

It is an arithmetic number, because the mean of its divisors is an integer number (108512511).

Almost surely, 2^217025021 is an apocalyptic number.

It is an amenable number.

217025021 is a deficient number, since it is larger than the sum of its proper divisors (1).

217025021 is an equidigital number, since it uses as much as digits as its factorization.

217025021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 217025021 is about 14731.7691062547. The cubic root of 217025021 is about 600.9475961665.

Adding to 217025021 its reverse (120520712), we get a palindrome (337545733).

The spelling of 217025021 in words is "two hundred seventeen million, twenty-five thousand, twenty-one".