672781 has 2 divisors, whose sum is σ = 672782. Its totient is φ = 672780.

The previous prime is 672779. The next prime is 672787. The reversal of 672781 is 187276.

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., 455625 + 217156 = 675^2 + 466^2 .

It is a cyclic number.

It is not a de Polignac number, because 672781 - 2¹ = 672779 is a prime.

It is a super-2 number, since 2×672781² = 905268547922, which contains 22 as substring.

Together with 672779, it forms a pair of twin primes.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (672787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336390 + 336391.

It is an arithmetic number, because the mean of its divisors is an integer number (336391).

2⁶⁷²⁷⁸¹ is an apocalyptic number.

It is an amenable number.

672781 is a deficient number, since it is larger than the sum of its proper divisors (1).

672781 is an equidigital number, since it uses as much as digits as its factorization.

672781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 31.

The square root of 672781 is about 820.2322841732. The cubic root of 672781 is about 87.6243022445.

The spelling of 672781 in words is "six hundred seventy-two thousand, seven hundred eighty-one".