81561230 has 16 divisors (see below), whose sum is σ = 147059280. Its totient is φ = 32569152.

The previous prime is 81561229. The next prime is 81561269. The reversal of 81561230 is 3216518.

It is a super-2 number, since 2×81561230² = 13304468478225800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81561230.

It is a congruent number.

It is an unprimeable number.

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, 440 + ... + 12779.

It is an arithmetic number, because the mean of its divisors is an integer number (9191205).

Almost surely, 2^81561230 is an apocalyptic number.

81561230 is a deficient number, since it is larger than the sum of its proper divisors (65498050).

81561230 is a wasteful number, since it uses less digits than its factorization.

81561230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13843.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 81561230 is about 9031.1256219809. The cubic root of 81561230 is about 433.6718728584.

Adding to 81561230 its reverse (3216518), we get a palindrome (84777748).

The spelling of 81561230 in words is "eighty-one million, five hundred sixty-one thousand, two hundred thirty".