8172409721 has 8 divisors (see below), whose sum is σ = 9498200640. Its totient is φ = 6886194768.

The previous prime is 8172409709. The next prime is 8172409723. The reversal of 8172409721 is 1279042718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 8172409721 - 2²² = 8168215417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8172409723) 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 in 7 ways as a sum of consecutive naturals, for example, 9893546 + ... + 9894371.

It is an arithmetic number, because the mean of its divisors is an integer number (1187275080).

Almost surely, 2^8172409721 is an apocalyptic number.

It is an amenable number.

8172409721 is a deficient number, since it is larger than the sum of its proper divisors (1325790919).

8172409721 is a wasteful number, since it uses less digits than its factorization.

8172409721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19787983.

The product of its (nonzero) digits is 56448, while the sum is 41.

The square root of 8172409721 is about 90401.3811896699. The cubic root of 8172409721 is about 2014.2654828263.

The spelling of 8172409721 in words is "eight billion, one hundred seventy-two million, four hundred nine thousand, seven hundred twenty-one".