8216178238921 has 2 divisors, whose sum is σ = 8216178238922. Its totient is φ = 8216178238920.

The previous prime is 8216178238909. The next prime is 8216178238937. The reversal of 8216178238921 is 1298328716128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7803860144521 + 412318094400 = 2793539^2 + 642120^2 .

It is a cyclic number.

It is not a de Polignac number, because 8216178238921 - 2⁵ = 8216178238889 is a prime.

It is not a weakly prime, because it can be changed into another prime (8216178239921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4108089119460 + 4108089119461.

It is an arithmetic number, because the mean of its divisors is an integer number (4108089119461).

Almost surely, 2^{8216178238921} is an apocalyptic number.

It is an amenable number.

8216178238921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8216178238921 is an equidigital number, since it uses as much as digits as its factorization.

8216178238921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4644864, while the sum is 58.

The spelling of 8216178238921 in words is "eight trillion, two hundred sixteen billion, one hundred seventy-eight million, two hundred thirty-eight thousand, nine hundred twenty-one".