161321978903 has 2 divisors, whose sum is σ = 161321978904. Its totient is φ = 161321978902.

The previous prime is 161321978897. The next prime is 161321978929. The reversal of 161321978903 is 309879123161.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161321978903 - 2⁴ = 161321978887 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161321908903) 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, 80660989451 + 80660989452.

It is an arithmetic number, because the mean of its divisors is an integer number (80660989452).

Almost surely, 2^161321978903 is an apocalyptic number.

161321978903 is a deficient number, since it is larger than the sum of its proper divisors (1).

161321978903 is an equidigital number, since it uses as much as digits as its factorization.

161321978903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 489888, while the sum is 50.

The spelling of 161321978903 in words is "one hundred sixty-one billion, three hundred twenty-one million, nine hundred seventy-eight thousand, nine hundred three".