81582121 has 4 divisors (see below), whose sum is σ = 81646992. Its totient is φ = 81517252.

The previous prime is 81582113. The next prime is 81582139. The reversal of 81582121 is 12128518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12128518 = 2 ⋅6064259.

It is a cyclic number.

It is not a de Polignac number, because 81582121 - 2³ = 81582113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81582121.

It is not an unprimeable number, because it can be changed into a prime (81582101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30511 + ... + 33076.

It is an arithmetic number, because the mean of its divisors is an integer number (20411748).

Almost surely, 2^81582121 is an apocalyptic number.

It is an amenable number.

81582121 is a deficient number, since it is larger than the sum of its proper divisors (64871).

81582121 is a wasteful number, since it uses less digits than its factorization.

81582121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64870.

The product of its digits is 1280, while the sum is 28.

The square root of 81582121 is about 9032.2821590116. The cubic root of 81582121 is about 433.7088964364.

The spelling of 81582121 in words is "eighty-one million, five hundred eighty-two thousand, one hundred twenty-one".