81590911 has 4 divisors (see below), whose sum is σ = 81610992. Its totient is φ = 81570832.

The previous prime is 81590897. The next prime is 81590917. The reversal of 81590911 is 11909518.

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 81590911 - 2¹⁷ = 81459839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81590917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1555 + ... + 12868.

It is an arithmetic number, because the mean of its divisors is an integer number (20402748).

Almost surely, 2^81590911 is an apocalyptic number.

81590911 is a deficient number, since it is larger than the sum of its proper divisors (20081).

81590911 is a wasteful number, since it uses less digits than its factorization.

81590911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20080.

The product of its (nonzero) digits is 3240, while the sum is 34.

The square root of 81590911 is about 9032.7687338933. The cubic root of 81590911 is about 433.7244724157.

The spelling of 81590911 in words is "eighty-one million, five hundred ninety thousand, nine hundred eleven".