1721066621 has 4 divisors (see below), whose sum is σ = 1822305852. Its totient is φ = 1619827392.

The previous prime is 1721066597. The next prime is 1721066623. The reversal of 1721066621 is 1266601271.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1434136900 + 286929721 = 37870^2 + 16939^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721066621 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721066623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50619590 + ... + 50619623.

It is an arithmetic number, because the mean of its divisors is an integer number (455576463).

Almost surely, 2^1721066621 is an apocalyptic number.

It is an amenable number.

1721066621 is a deficient number, since it is larger than the sum of its proper divisors (101239231).

1721066621 is a wasteful number, since it uses less digits than its factorization.

1721066621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101239230.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 1721066621 is about 41485.7399717059. The cubic root of 1721066621 is about 1198.3928998090.

Adding to 1721066621 its reverse (1266601271), we get a palindrome (2987667892).

The spelling of 1721066621 in words is "one billion, seven hundred twenty-one million, sixty-six thousand, six hundred twenty-one".