168904781 has 2 divisors, whose sum is σ = 168904782. Its totient is φ = 168904780.

The previous prime is 168904759. The next prime is 168904807. The reversal of 168904781 is 187409861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157276681 + 11628100 = 12541^2 + 3410^2 .

It is a cyclic number.

It is not a de Polignac number, because 168904781 - 2⁶ = 168904717 is a prime.

It is a super-2 number, since 2×168904781² = 57057650089315922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168904721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84452390 + 84452391.

It is an arithmetic number, because the mean of its divisors is an integer number (84452391).

Almost surely, 2^168904781 is an apocalyptic number.

It is an amenable number.

168904781 is a deficient number, since it is larger than the sum of its proper divisors (1).

168904781 is an equidigital number, since it uses as much as digits as its factorization.

168904781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96768, while the sum is 44.

The square root of 168904781 is about 12996.3372147694. The cubic root of 168904781 is about 552.7736266715.

The spelling of 168904781 in words is "one hundred sixty-eight million, nine hundred four thousand, seven hundred eighty-one".