216772021 has 2 divisors, whose sum is σ = 216772022. Its totient is φ = 216772020.

The previous prime is 216772019. The next prime is 216772051. The reversal of 216772021 is 120277612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 124880625 + 91891396 = 11175^2 + 9586^2 .

It is a cyclic number.

It is not a de Polignac number, because 216772021 - 2¹ = 216772019 is a prime.

Together with 216772019, 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 (216772051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108386010 + 108386011.

It is an arithmetic number, because the mean of its divisors is an integer number (108386011).

Almost surely, 2^216772021 is an apocalyptic number.

It is an amenable number.

216772021 is a deficient number, since it is larger than the sum of its proper divisors (1).

216772021 is an equidigital number, since it uses as much as digits as its factorization.

216772021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 216772021 is about 14723.1797177104. The cubic root of 216772021 is about 600.7139842996.

The spelling of 216772021 in words is "two hundred sixteen million, seven hundred seventy-two thousand, twenty-one".