81390049 has 8 divisors (see below), whose sum is σ = 88708032.
Its totient is φ = 74223120.
The previous prime is 81390019. The next prime is 81390061. The reversal of 81390049 is 94009318.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 81390049 - 213 = 81381857 is a prime.
It is a Duffinian number.
It is a junction number, because it is equal to n+sod(n) for n = 81389996 and 81390023.
It is not an unprimeable number, because it can be changed into a prime (81390019) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36637 + ... + 38794.
It is an arithmetic number, because the mean of its divisors is an integer number (11088504).
Almost surely, 281390049 is an apocalyptic number.
It is an amenable number.
81390049 is a deficient number, since it is larger than the sum of its proper divisors (7317983).
81390049 is a wasteful number, since it uses less digits than its factorization.
81390049 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 75527.
The product of its (nonzero) digits is 7776, while the sum is 34.
The square root of 81390049 is about 9021.6433647091.
The cubic root of 81390049 is about 433.3682629963.
The spelling of 81390049 in words is "eighty-one million, three hundred ninety thousand, forty-nine".