168996781 has 2 divisors, whose sum is σ = 168996782. Its totient is φ = 168996780.

The previous prime is 168996769. The next prime is 168996809. The reversal of 168996781 is 187699861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102313225 + 66683556 = 10115^2 + 8166^2 .

It is a cyclic number.

It is not a de Polignac number, because 168996781 - 2⁵ = 168996749 is a prime.

It is a super-2 number, since 2×168996781² = 57119823976723922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168996181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84498390 + 84498391.

It is an arithmetic number, because the mean of its divisors is an integer number (84498391).

Almost surely, 2^168996781 is an apocalyptic number.

It is an amenable number.

168996781 is a deficient number, since it is larger than the sum of its proper divisors (1).

168996781 is an equidigital number, since it uses as much as digits as its factorization.

168996781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1306368, while the sum is 55.

The square root of 168996781 is about 12999.8761917181. The cubic root of 168996781 is about 552.8739710643.

The spelling of 168996781 in words is "one hundred sixty-eight million, nine hundred ninety-six thousand, seven hundred eighty-one".