8172909421 has 2 divisors, whose sum is σ = 8172909422. Its totient is φ = 8172909420.

The previous prime is 8172909403. The next prime is 8172909449. The reversal of 8172909421 is 1249092718.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8097480196 + 75429225 = 89986^2 + 8685^2 .

It is a cyclic number.

It is not a de Polignac number, because 8172909421 - 2⁵ = 8172909389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8172909491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4086454710 + 4086454711.

It is an arithmetic number, because the mean of its divisors is an integer number (4086454711).

Almost surely, 2^8172909421 is an apocalyptic number.

It is an amenable number.

8172909421 is a deficient number, since it is larger than the sum of its proper divisors (1).

8172909421 is an equidigital number, since it uses as much as digits as its factorization.

8172909421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 43.

The square root of 8172909421 is about 90404.1449326302. The cubic root of 8172909421 is about 2014.3065359135.

The spelling of 8172909421 in words is "eight billion, one hundred seventy-two million, nine hundred nine thousand, four hundred twenty-one".