161565503989 has 2 divisors, whose sum is σ = 161565503990. Its totient is φ = 161565503988.

The previous prime is 161565503977. The next prime is 161565504019. The reversal of 161565503989 is 989305565161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 95499540900 + 66065963089 = 309030^2 + 257033^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161565503989 is a prime.

It is a super-2 number, since 2×161565503989² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161565503929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80782751994 + 80782751995.

It is an arithmetic number, because the mean of its divisors is an integer number (80782751995).

Almost surely, 2^161565503989 is an apocalyptic number.

It is an amenable number.

161565503989 is a deficient number, since it is larger than the sum of its proper divisors (1).

161565503989 is an equidigital number, since it uses as much as digits as its factorization.

161565503989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748000, while the sum is 58.

The spelling of 161565503989 in words is "one hundred sixty-one billion, five hundred sixty-five million, five hundred three thousand, nine hundred eighty-nine".