17965657921 has 2 divisors, whose sum is σ = 17965657922. Its totient is φ = 17965657920.

The previous prime is 17965657883. The next prime is 17965657981. The reversal of 17965657921 is 12975656971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11016601600 + 6949056321 = 104960^2 + 83361^2 .

It is a cyclic number.

It is not a de Polignac number, because 17965657921 - 2⁷ = 17965657793 is a prime.

It is not a weakly prime, because it can be changed into another prime (17965657981) 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 as a sum of consecutive naturals, namely, 8982828960 + 8982828961.

It is an arithmetic number, because the mean of its divisors is an integer number (8982828961).

Almost surely, 2^17965657921 is an apocalyptic number.

It is an amenable number.

17965657921 is a deficient number, since it is larger than the sum of its proper divisors (1).

17965657921 is an equidigital number, since it uses as much as digits as its factorization.

17965657921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7144200, while the sum is 58.

The spelling of 17965657921 in words is "seventeen billion, nine hundred sixty-five million, six hundred fifty-seven thousand, nine hundred twenty-one".