81680738 has 8 divisors (see below), whose sum is σ = 124832988. Its totient is φ = 40069744.

The previous prime is 81680737. The next prime is 81680747. The reversal of 81680738 is 83708618.

It can be written as a sum of positive squares in 2 ways, for example, as 65334889 + 16345849 = 8083^2 + 4043^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 81680695 and 81680704.

It is not an unprimeable number, because it can be changed into a prime (81680737) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 385181 + ... + 385392.

Almost surely, 2^81680738 is an apocalyptic number.

81680738 is a deficient number, since it is larger than the sum of its proper divisors (43152250).

81680738 is a wasteful number, since it uses less digits than its factorization.

81680738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 770628.

The product of its (nonzero) digits is 64512, while the sum is 41.

The square root of 81680738 is about 9037.7396510411. The cubic root of 81680738 is about 433.8835827823.

The spelling of 81680738 in words is "eighty-one million, six hundred eighty thousand, seven hundred thirty-eight".