16228638721 has 2 divisors, whose sum is σ = 16228638722. Its totient is φ = 16228638720.

The previous prime is 16228638703. The next prime is 16228638731. The reversal of 16228638721 is 12783682261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10068115600 + 6160523121 = 100340^2 + 78489^2 .

It is a cyclic number.

It is not a de Polignac number, because 16228638721 - 2⁵ = 16228638689 is a prime.

It is not a weakly prime, because it can be changed into another prime (16228638731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8114319360 + 8114319361.

It is an arithmetic number, because the mean of its divisors is an integer number (8114319361).

Almost surely, 2^16228638721 is an apocalyptic number.

It is an amenable number.

16228638721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16228638721 is an equidigital number, since it uses as much as digits as its factorization.

16228638721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 387072, while the sum is 46.

The spelling of 16228638721 in words is "sixteen billion, two hundred twenty-eight million, six hundred thirty-eight thousand, seven hundred twenty-one".