81689782 has 4 divisors (see below), whose sum is σ = 122534676. Its totient is φ = 40844890.

The previous prime is 81689737. The next prime is 81689789. The reversal of 81689782 is 28798618.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689789) 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, 20422444 + ... + 20422447.

It is an arithmetic number, because the mean of its divisors is an integer number (30633669).

Almost surely, 2^81689782 is an apocalyptic number.

81689782 is a deficient number, since it is larger than the sum of its proper divisors (40844894).

81689782 is a wasteful number, since it uses less digits than its factorization.

81689782 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40844893.

The product of its digits is 387072, while the sum is 49.

The square root of 81689782 is about 9038.2399835366. The cubic root of 81689782 is about 433.8995959346.

The spelling of 81689782 in words is "eighty-one million, six hundred eighty-nine thousand, seven hundred eighty-two".