1671605621 has 4 divisors (see below), whose sum is σ = 1910406432. Its totient is φ = 1432804812.

The previous prime is 1671605603. The next prime is 1671605633. The reversal of 1671605621 is 1265061761.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1671605621 - 2⁶ = 1671605557 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 (1671605671) 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, 119400395 + ... + 119400408.

It is an arithmetic number, because the mean of its divisors is an integer number (477601608).

Almost surely, 2^1671605621 is an apocalyptic number.

It is an amenable number.

1671605621 is a deficient number, since it is larger than the sum of its proper divisors (238800811).

1671605621 is an equidigital number, since it uses as much as digits as its factorization.

1671605621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238800810.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 1671605621 is about 40885.2738892624. The cubic root of 1671605621 is about 1186.8011021140.

The spelling of 1671605621 in words is "one billion, six hundred seventy-one million, six hundred five thousand, six hundred twenty-one".