161621543569 has 2 divisors, whose sum is σ = 161621543570. Its totient is φ = 161621543568.

The previous prime is 161621543563. The next prime is 161621543593. The reversal of 161621543569 is 965345126161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 161459312400 + 162231169 = 401820^2 + 12737^2 .

It is a cyclic number.

It is not a de Polignac number, because 161621543569 - 2⁷ = 161621543441 is a prime.

It is a super-2 number, since 2×161621543569² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161621543563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80810771784 + 80810771785.

It is an arithmetic number, because the mean of its divisors is an integer number (80810771785).

Almost surely, 2^161621543569 is an apocalyptic number.

It is an amenable number.

161621543569 is a deficient number, since it is larger than the sum of its proper divisors (1).

161621543569 is an equidigital number, since it uses as much as digits as its factorization.

161621543569 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1166400, while the sum is 49.

The spelling of 161621543569 in words is "one hundred sixty-one billion, six hundred twenty-one million, five hundred forty-three thousand, five hundred sixty-nine".