17381521921 has 3 divisors (see below), whose sum is σ = 17381653761. Its totient is φ = 17381390082.

The previous prime is 17381521909. The next prime is 17381521943. The reversal of 17381521921 is 12912518371.

The square root of 17381521921 is 131839.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 17381521921 - 2⁷ = 17381521793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17381521721) 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 2 ways as a sum of consecutive naturals, for example, 65920 + ... + 197758.

It is an arithmetic number, because the mean of its divisors is an integer number (5793884587).

Almost surely, 2^17381521921 is an apocalyptic number.

17381521921 is the 131839-th square number.

17381521921 is the 65920-th centered octagonal number.

It is an amenable number.

17381521921 is a deficient number, since it is larger than the sum of its proper divisors (131840).

17381521921 is an frugal number, since it uses more digits than its factorization.

17381521921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263678 (or 131839 counting only the distinct ones).

The product of its digits is 30240, while the sum is 40.

The spelling of 17381521921 in words is "seventeen billion, three hundred eighty-one million, five hundred twenty-one thousand, nine hundred twenty-one".