81573646 has 32 divisors (see below), whose sum is σ = 153031680. Its totient is φ = 31682400.

The previous prime is 81573601. The next prime is 81573647. The reversal of 81573646 is 64637518.

It is a happy number.

Its product of digits (120960) is a multiple of the sum of its prime divisors (1680).

It is a junction number, because it is equal to n+sod(n) for n = 81573599 and 81573608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81573647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 65760 + ... + 66988.

It is an arithmetic number, because the mean of its divisors is an integer number (4782240).

Almost surely, 2^81573646 is an apocalyptic number.

81573646 is a deficient number, since it is larger than the sum of its proper divisors (71458034).

81573646 is a wasteful number, since it uses less digits than its factorization.

81573646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1680.

The product of its digits is 120960, while the sum is 40.

The square root of 81573646 is about 9031.8129962926. The cubic root of 81573646 is about 433.6938775812.

The spelling of 81573646 in words is "eighty-one million, five hundred seventy-three thousand, six hundred forty-six".