1721431121 has 8 divisors (see below), whose sum is σ = 1734777000. Its totient is φ = 1708109440.

The previous prime is 1721431111. The next prime is 1721431123. The reversal of 1721431121 is 1211341271.

It can be written as a sum of positive squares in 4 ways, for example, as 4157521 + 1717273600 = 2039^2 + 41440^2 .

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 1721431121 - 2¹⁰ = 1721430097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721431123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152645 + ... + 163533.

It is an arithmetic number, because the mean of its divisors is an integer number (216847125).

Almost surely, 2^1721431121 is an apocalyptic number.

It is an amenable number.

1721431121 is a deficient number, since it is larger than the sum of its proper divisors (13345879).

1721431121 is a wasteful number, since it uses less digits than its factorization.

1721431121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12099.

The product of its digits is 336, while the sum is 23.

The square root of 1721431121 is about 41490.1328149236. The cubic root of 1721431121 is about 1198.4774952905.

Adding to 1721431121 its reverse (1211341271), we get a palindrome (2932772392).

The spelling of 1721431121 in words is "one billion, seven hundred twenty-one million, four hundred thirty-one thousand, one hundred twenty-one".