81689679 has 12 divisors (see below), whose sum is σ = 119418936. Its totient is φ = 53803152.

The previous prime is 81689677. The next prime is 81689711. The reversal of 81689679 is 97698618.

It is not a de Polignac number, because 81689679 - 2¹ = 81689677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689677) 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 in 11 ways as a sum of consecutive naturals, for example, 53932 + ... + 55425.

It is an arithmetic number, because the mean of its divisors is an integer number (9951578).

Almost surely, 2^81689679 is an apocalyptic number.

81689679 is a deficient number, since it is larger than the sum of its proper divisors (37729257).

81689679 is a wasteful number, since it uses less digits than its factorization.

81689679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109446 (or 109443 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 54.

The square root of 81689679 is about 9038.2342855228. The cubic root of 81689679 is about 433.8994135712.

The spelling of 81689679 in words is "eighty-one million, six hundred eighty-nine thousand, six hundred seventy-nine".