81745648 has 20 divisors (see below), whose sum is σ = 159052320. Its totient is φ = 40699904.

The previous prime is 81745633. The next prime is 81745649. The reversal of 81745648 is 84654718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81745649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6865 + ... + 14512.

It is an arithmetic number, because the mean of its divisors is an integer number (7952616).

Almost surely, 2^81745648 is an apocalyptic number.

It is an amenable number.

81745648 is a deficient number, since it is larger than the sum of its proper divisors (77306672).

81745648 is a wasteful number, since it uses less digits than its factorization.

81745648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21624 (or 21618 counting only the distinct ones).

The product of its digits is 215040, while the sum is 43.

The square root of 81745648 is about 9041.3299906596. The cubic root of 81745648 is about 433.9984851328.

The spelling of 81745648 in words is "eighty-one million, seven hundred forty-five thousand, six hundred forty-eight".