681644338 has 4 divisors (see below), whose sum is σ = 1022466510. Its totient is φ = 340822168.

The previous prime is 681644297. The next prime is 681644339. The reversal of 681644338 is 833446186.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 681366609 + 277729 = 26103^2 + 527^2 .

It is a junction number, because it is equal to n+sod(n) for n = 681644294 and 681644303.

It is not an unprimeable number, because it can be changed into a prime (681644339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 170411083 + ... + 170411086.

Almost surely, 2^681644338 is an apocalyptic number.

681644338 is a deficient number, since it is larger than the sum of its proper divisors (340822172).

681644338 is a wasteful number, since it uses less digits than its factorization.

681644338 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340822171.

The product of its digits is 331776, while the sum is 43.

The square root of 681644338 is about 26108.3193254564. The cubic root of 681644338 is about 880.0741750493.

The spelling of 681644338 in words is "six hundred eighty-one million, six hundred forty-four thousand, three hundred thirty-eight".