1681667321 has 4 divisors (see below), whose sum is σ = 1681997952. Its totient is φ = 1681336692.

The previous prime is 1681667311. The next prime is 1681667327. The reversal of 1681667321 is 1237661861.

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 1681667321 - 2¹⁴ = 1681650937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1681667327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157565 + ... + 167898.

It is an arithmetic number, because the mean of its divisors is an integer number (420499488).

Almost surely, 2^1681667321 is an apocalyptic number.

It is an amenable number.

1681667321 is a deficient number, since it is larger than the sum of its proper divisors (330631).

1681667321 is an equidigital number, since it uses as much as digits as its factorization.

1681667321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330630.

The product of its digits is 72576, while the sum is 41.

The square root of 1681667321 is about 41008.1372534769. The cubic root of 1681667321 is about 1189.1775313922.

The spelling of 1681667321 in words is "one billion, six hundred eighty-one million, six hundred sixty-seven thousand, three hundred twenty-one".