1671540221 has 16 divisors (see below), whose sum is σ = 1816273200. Its totient is φ = 1529169408.

The previous prime is 1671540217. The next prime is 1671540229. The reversal of 1671540221 is 1220451761.

It can be written as a sum of positive squares in 8 ways, for example, as 56625625 + 1614914596 = 7525^2 + 40186^2 .

It is not a de Polignac number, because 1671540221 - 2² = 1671540217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1671540229) 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 15 ways as a sum of consecutive naturals, for example, 1038065 + ... + 1039673.

It is an arithmetic number, because the mean of its divisors is an integer number (113517075).

Almost surely, 2^1671540221 is an apocalyptic number.

It is an amenable number.

1671540221 is a deficient number, since it is larger than the sum of its proper divisors (144732979).

1671540221 is a wasteful number, since it uses less digits than its factorization.

1671540221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2288.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 1671540221 is about 40884.4740824680. The cubic root of 1671540221 is about 1186.7856244193.

Adding to 1671540221 its reverse (1220451761), we get a palindrome (2891991982).

It can be divided in two parts, 1671540 and 221, that added together give a palindrome (1671761).

The spelling of 1671540221 in words is "one billion, six hundred seventy-one million, five hundred forty thousand, two hundred twenty-one".