81959387 has 4 divisors (see below), whose sum is σ = 82509600.
Its totient is φ = 81409176.
The previous prime is 81959377. The next prime is 81959401. The reversal of 81959387 is 78395918.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 81959387 - 28 = 81959131 is a prime.
It is a super-2 number, since 2×819593872 = 13434682234831538, which contains 22 as substring.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (81959357) 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, 274883 + ... + 275180.
It is an arithmetic number, because the mean of its divisors is an integer number (20627400).
Almost surely, 281959387 is an apocalyptic number.
81959387 is a deficient number, since it is larger than the sum of its proper divisors (550213).
81959387 is a wasteful number, since it uses less digits than its factorization.
81959387 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 550212.
The product of its digits is 544320, while the sum is 50.
The square root of 81959387 is about 9053.1423826205.
The cubic root of 81959387 is about 434.3764121687.
It can be divided in two parts, 819 and 59387, that added together give a palindrome (60206).
The spelling of 81959387 in words is "eighty-one million, nine hundred fifty-nine thousand, three hundred eighty-seven".