81585398 has 4 divisors (see below), whose sum is σ = 122378100. Its totient is φ = 40792698.

The previous prime is 81585353. The next prime is 81585401. The reversal of 81585398 is 89358518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89358518 = 2 ⋅44679259.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20396348 + ... + 20396351.

It is an arithmetic number, because the mean of its divisors is an integer number (30594525).

Almost surely, 2^81585398 is an apocalyptic number.

81585398 is a deficient number, since it is larger than the sum of its proper divisors (40792702).

81585398 is a wasteful number, since it uses less digits than its factorization.

81585398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40792701.

The product of its digits is 345600, while the sum is 47.

The square root of 81585398 is about 9032.4635620632. The cubic root of 81585398 is about 433.7147034482.

The spelling of 81585398 in words is "eighty-one million, five hundred eighty-five thousand, three hundred ninety-eight".