81564231 has 8 divisors (see below), whose sum is σ = 124288384. Its totient is φ = 46608120.

The previous prime is 81564229. The next prime is 81564253. The reversal of 81564231 is 13246518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81564231 - 2¹ = 81564229 is a prime.

It is a super-2 number, since 2×81564231² = 13305447557242722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81564631) 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 7 ways as a sum of consecutive naturals, for example, 1941985 + ... + 1942026.

It is an arithmetic number, because the mean of its divisors is an integer number (15536048).

Almost surely, 2^81564231 is an apocalyptic number.

81564231 is a deficient number, since it is larger than the sum of its proper divisors (42724153).

81564231 is a wasteful number, since it uses less digits than its factorization.

81564231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3884021.

The product of its digits is 5760, while the sum is 30.

The square root of 81564231 is about 9031.2917680695. The cubic root of 81564231 is about 433.6771916981.

The spelling of 81564231 in words is "eighty-one million, five hundred sixty-four thousand, two hundred thirty-one".