28172632721 has 2 divisors, whose sum is σ = 28172632722. Its totient is φ = 28172632720.

The previous prime is 28172632711. The next prime is 28172632727. The reversal of 28172632721 is 12723627182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22880797696 + 5291835025 = 151264^2 + 72745^2 .

It is a cyclic number.

It is not a de Polignac number, because 28172632721 - 2²⁶ = 28105523857 is a prime.

It is not a weakly prime, because it can be changed into another prime (28172632727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14086316360 + 14086316361.

It is an arithmetic number, because the mean of its divisors is an integer number (14086316361).

Almost surely, 2^28172632721 is an apocalyptic number.

It is an amenable number.

28172632721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28172632721 is an equidigital number, since it uses as much as digits as its factorization.

28172632721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 112896, while the sum is 41.

The spelling of 28172632721 in words is "twenty-eight billion, one hundred seventy-two million, six hundred thirty-two thousand, seven hundred twenty-one".