172112823821 has 2 divisors, whose sum is σ = 172112823822. Its totient is φ = 172112823820.

The previous prime is 172112823793. The next prime is 172112823889. The reversal of 172112823821 is 128328211271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135626475625 + 36486348196 = 368275^2 + 191014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-172112823821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172112823721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86056411910 + 86056411911.

It is an arithmetic number, because the mean of its divisors is an integer number (86056411911).

Almost surely, 2^172112823821 is an apocalyptic number.

It is an amenable number.

172112823821 is a deficient number, since it is larger than the sum of its proper divisors (1).

172112823821 is an equidigital number, since it uses as much as digits as its factorization.

172112823821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21504, while the sum is 38.

The spelling of 172112823821 in words is "one hundred seventy-two billion, one hundred twelve million, eight hundred twenty-three thousand, eight hundred twenty-one".