673615781 has 2 divisors, whose sum is σ = 673615782. Its totient is φ = 673615780.

The previous prime is 673615687. The next prime is 673615793. The reversal of 673615781 is 187516376.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 668481025 + 5134756 = 25855^2 + 2266^2 .

It is a cyclic number.

It is not a de Polignac number, because 673615781 - 2²⁶ = 606506917 is a prime.

It is a super-2 number, since 2×673615781² = 907516440824479922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (673615381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336807890 + 336807891.

It is an arithmetic number, because the mean of its divisors is an integer number (336807891).

Almost surely, 2^673615781 is an apocalyptic number.

It is an amenable number.

673615781 is a deficient number, since it is larger than the sum of its proper divisors (1).

673615781 is an equidigital number, since it uses as much as digits as its factorization.

673615781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 211680, while the sum is 44.

The square root of 673615781 is about 25954.1091351639. The cubic root of 673615781 is about 876.6052843110.

The spelling of 673615781 in words is "six hundred seventy-three million, six hundred fifteen thousand, seven hundred eighty-one".