161688257 has 2 divisors, whose sum is σ = 161688258. Its totient is φ = 161688256.

The previous prime is 161688251. The next prime is 161688269. The reversal of 161688257 is 752886161.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159794881 + 1893376 = 12641^2 + 1376^2 .

It is a cyclic number.

It is not a de Polignac number, because 161688257 - 2¹⁸ = 161426113 is a prime.

It is a super-2 number, since 2×161688257² = 52286184903396098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161688251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80844128 + 80844129.

It is an arithmetic number, because the mean of its divisors is an integer number (80844129).

Almost surely, 2^161688257 is an apocalyptic number.

It is an amenable number.

161688257 is a deficient number, since it is larger than the sum of its proper divisors (1).

161688257 is an equidigital number, since it uses as much as digits as its factorization.

161688257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 161280, while the sum is 44.

The square root of 161688257 is about 12715.6697424870. The cubic root of 161688257 is about 544.7862776169.

The spelling of 161688257 in words is "one hundred sixty-one million, six hundred eighty-eight thousand, two hundred fifty-seven".