161551543 has 2 divisors, whose sum is σ = 161551544. Its totient is φ = 161551542.

The previous prime is 161551541. The next prime is 161551567. The reversal of 161551543 is 345155161.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161551543 - 2¹ = 161551541 is a prime.

Together with 161551541, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161551541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80775771 + 80775772.

It is an arithmetic number, because the mean of its divisors is an integer number (80775772).

Almost surely, 2^161551543 is an apocalyptic number.

161551543 is a deficient number, since it is larger than the sum of its proper divisors (1).

161551543 is an equidigital number, since it uses as much as digits as its factorization.

161551543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9000, while the sum is 31.

The square root of 161551543 is about 12710.2927975716. The cubic root of 161551543 is about 544.6326879987.

The spelling of 161551543 in words is "one hundred sixty-one million, five hundred fifty-one thousand, five hundred forty-three".