321661643 has 2 divisors, whose sum is σ = 321661644. Its totient is φ = 321661642.

The previous prime is 321661633. The next prime is 321661651. The reversal of 321661643 is 346166123.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-321661643 is a prime.

It is a super-3 number, since 3×321661643³ (a number of 26 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (321661633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160830821 + 160830822.

It is an arithmetic number, because the mean of its divisors is an integer number (160830822).

Almost surely, 2^321661643 is an apocalyptic number.

321661643 is a deficient number, since it is larger than the sum of its proper divisors (1).

321661643 is an equidigital number, since it uses as much as digits as its factorization.

321661643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 32.

The square root of 321661643 is about 17934.9280176978. The cubic root of 321661643 is about 685.1722393524.

The spelling of 321661643 in words is "three hundred twenty-one million, six hundred sixty-one thousand, six hundred forty-three".