168400781 has 4 divisors (see below), whose sum is σ = 177264000. Its totient is φ = 159537564.

The previous prime is 168400723. The next prime is 168400829. The reversal of 168400781 is 187004861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 168400781 - 2⁶ = 168400717 is a prime.

It is a super-2 number, since 2×168400781² = 56717646082819922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168400381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4431581 + ... + 4431618.

It is an arithmetic number, because the mean of its divisors is an integer number (44316000).

Almost surely, 2^168400781 is an apocalyptic number.

It is an amenable number.

168400781 is a deficient number, since it is larger than the sum of its proper divisors (8863219).

168400781 is an equidigital number, since it uses as much as digits as its factorization.

168400781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8863218.

The product of its (nonzero) digits is 10752, while the sum is 35.

The square root of 168400781 is about 12976.9326498984. The cubic root of 168400781 is about 552.2232663402.

The spelling of 168400781 in words is "one hundred sixty-eight million, four hundred thousand, seven hundred eighty-one".