838217021 has 2 divisors, whose sum is σ = 838217022. Its totient is φ = 838217020.

The previous prime is 838216969. The next prime is 838217047. The reversal of 838217021 is 120712838.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 630712996 + 207504025 = 25114^2 + 14405^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-838217021 is a prime.

It is a super-2 number, since 2×838217021² = 1405215548588228882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (838217321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 419108510 + 419108511.

It is an arithmetic number, because the mean of its divisors is an integer number (419108511).

Almost surely, 2^838217021 is an apocalyptic number.

It is an amenable number.

838217021 is a deficient number, since it is larger than the sum of its proper divisors (1).

838217021 is an equidigital number, since it uses as much as digits as its factorization.

838217021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 838217021 is about 28951.9778426276. The cubic root of 838217021 is about 942.8707398920.

Adding to 838217021 its reverse (120712838), we get a palindrome (958929859).

The spelling of 838217021 in words is "eight hundred thirty-eight million, two hundred seventeen thousand, twenty-one".