681945919 has 2 divisors, whose sum is σ = 681945920. Its totient is φ = 681945918.

The previous prime is 681945893. The next prime is 681945941. The reversal of 681945919 is 919549186.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 681945919 - 2¹⁵ = 681913151 is a prime.

It is a super-2 number, since 2×681945919² = 930100472881509122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681945959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340972959 + 340972960.

It is an arithmetic number, because the mean of its divisors is an integer number (340972960).

Almost surely, 2^681945919 is an apocalyptic number.

681945919 is a deficient number, since it is larger than the sum of its proper divisors (1).

681945919 is an equidigital number, since it uses as much as digits as its factorization.

681945919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 52.

The square root of 681945919 is about 26114.0942596139. The cubic root of 681945919 is about 880.2039467900.

The spelling of 681945919 in words is "six hundred eighty-one million, nine hundred forty-five thousand, nine hundred nineteen".