161856437 has 2 divisors, whose sum is σ = 161856438. Its totient is φ = 161856436.

The previous prime is 161856427. The next prime is 161856491. The reversal of 161856437 is 734658161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 118940836 + 42915601 = 10906^2 + 6551^2 .

It is a cyclic number.

It is not a de Polignac number, because 161856437 - 2¹⁴ = 161840053 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 161856394 and 161856403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161856407) 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, 80928218 + 80928219.

It is an arithmetic number, because the mean of its divisors is an integer number (80928219).

Almost surely, 2^161856437 is an apocalyptic number.

It is an amenable number.

161856437 is a deficient number, since it is larger than the sum of its proper divisors (1).

161856437 is an equidigital number, since it uses as much as digits as its factorization.

161856437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 41.

The square root of 161856437 is about 12722.2811240752. The cubic root of 161856437 is about 544.9750986013.

It can be divided in two parts, 16185 and 6437, that added together give a palindrome (22622).

The spelling of 161856437 in words is "one hundred sixty-one million, eight hundred fifty-six thousand, four hundred thirty-seven".