81678706 has 4 divisors (see below), whose sum is σ = 122518062. Its totient is φ = 40839352.

The previous prime is 81678697. The next prime is 81678743. The reversal of 81678706 is 60787618.

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., 63059481 + 18619225 = 7941^2 + 4315^2 .

It is a super-2 number, since 2×81678706² = 13342822027668872, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20419675 + ... + 20419678.

Almost surely, 2^81678706 is an apocalyptic number.

81678706 is a deficient number, since it is larger than the sum of its proper divisors (40839356).

81678706 is a wasteful number, since it uses less digits than its factorization.

81678706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40839355.

The product of its (nonzero) digits is 112896, while the sum is 43.

The square root of 81678706 is about 9037.6272328527. The cubic root of 81678706 is about 433.8799847951.

The spelling of 81678706 in words is "eighty-one million, six hundred seventy-eight thousand, seven hundred six".