81561060 has 96 divisors (see below), whose sum is σ = 290008320. Its totient is φ = 18641664.

The previous prime is 81561049. The next prime is 81561089. The reversal of 81561060 is 6016518.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 31 ways as a sum of consecutive naturals, for example, 7009 + ... + 14568.

It is an arithmetic number, because the mean of its divisors is an integer number (3020920).

Almost surely, 2^81561060 is an apocalyptic number.

It is an amenable number.

81561060 is an abundant number, since it is smaller than the sum of its proper divisors (208447260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81561060 is a wasteful number, since it uses less digits than its factorization.

81561060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21602 (or 21594 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 81561060 is about 9031.1162100817. The cubic root of 81561060 is about 433.6715715540.

Adding to 81561060 its reverse (6016518), we get a palindrome (87577578).

It can be divided in two parts, 8156 and 1060, that added together give a square (9216 = 96²).

The spelling of 81561060 in words is "eighty-one million, five hundred sixty-one thousand, sixty".