321691387 has 2 divisors, whose sum is σ = 321691388. Its totient is φ = 321691386.

The previous prime is 321691313. The next prime is 321691417. The reversal of 321691387 is 783196123.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-321691387 is a prime.

It is not a weakly prime, because it can be changed into another prime (321691687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160845693 + 160845694.

It is an arithmetic number, because the mean of its divisors is an integer number (160845694).

Almost surely, 2^321691387 is an apocalyptic number.

321691387 is a deficient number, since it is larger than the sum of its proper divisors (1).

321691387 is an equidigital number, since it uses as much as digits as its factorization.

321691387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 321691387 is about 17935.7572184728. The cubic root of 321691387 is about 685.1933579568.

The spelling of 321691387 in words is "three hundred twenty-one million, six hundred ninety-one thousand, three hundred eighty-seven".