81725566 has 16 divisors (see below), whose sum is σ = 132187104. Its totient is φ = 37671264.

The previous prime is 81725551. The next prime is 81725573. The reversal of 81725566 is 66552718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26160 + ... + 29116.

It is an arithmetic number, because the mean of its divisors is an integer number (8261694).

Almost surely, 2^81725566 is an apocalyptic number.

81725566 is a deficient number, since it is larger than the sum of its proper divisors (50461538).

81725566 is a wasteful number, since it uses less digits than its factorization.

81725566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4035.

The product of its digits is 100800, while the sum is 40.

The square root of 81725566 is about 9040.2193557457. The cubic root of 81725566 is about 433.9629428885.

The spelling of 81725566 in words is "eighty-one million, seven hundred twenty-five thousand, five hundred sixty-six".