168501661 has 2 divisors, whose sum is σ = 168501662. Its totient is φ = 168501660.

The previous prime is 168501659. The next prime is 168501689. The reversal of 168501661 is 166105861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116748025 + 51753636 = 10805^2 + 7194^2 .

It is a cyclic number.

It is not a de Polignac number, because 168501661 - 2¹ = 168501659 is a prime.

Together with 168501659, 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 (168501601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84250830 + 84250831.

It is an arithmetic number, because the mean of its divisors is an integer number (84250831).

Almost surely, 2^168501661 is an apocalyptic number.

It is an amenable number.

168501661 is a deficient number, since it is larger than the sum of its proper divisors (1).

168501661 is an equidigital number, since it uses as much as digits as its factorization.

168501661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 168501661 is about 12980.8189649190. The cubic root of 168501661 is about 552.3335135781. Note that the first 3 decimals are identical.

The spelling of 168501661 in words is "one hundred sixty-eight million, five hundred one thousand, six hundred sixty-one".