20171038721 has 8 divisors (see below), whose sum is σ = 20316980544. Its totient is φ = 20025396720.

The previous prime is 20171038717. The next prime is 20171038753. The reversal of 20171038721 is 12783017102.

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 20171038721 - 2² = 20171038717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20171008721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60971 + ... + 209903.

It is an arithmetic number, because the mean of its divisors is an integer number (2539622568).

Almost surely, 2^20171038721 is an apocalyptic number.

It is an amenable number.

20171038721 is a deficient number, since it is larger than the sum of its proper divisors (145941823).

20171038721 is a wasteful number, since it uses less digits than its factorization.

20171038721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149911.

The product of its (nonzero) digits is 4704, while the sum is 32.

The spelling of 20171038721 in words is "twenty billion, one hundred seventy-one million, thirty-eight thousand, seven hundred twenty-one".