81993648 has 40 divisors (see below), whose sum is σ = 231074496. Its totient is φ = 24846400.

The previous prime is 81993641. The next prime is 81993649. The reversal of 81993648 is 84639918.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 81993597 and 81993606.

It is not an unprimeable number, because it can be changed into a prime (81993641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77118 + ... + 78173.

Almost surely, 2^81993648 is an apocalyptic number.

81993648 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

81993648 is an abundant number, since it is smaller than the sum of its proper divisors (149080848).

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

81993648 is a wasteful number, since it uses less digits than its factorization.

81993648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155313 (or 155307 counting only the distinct ones).

The product of its digits is 373248, while the sum is 48.

The square root of 81993648 is about 9055.0344008181. The cubic root of 81993648 is about 434.4369303415.

The spelling of 81993648 in words is "eighty-one million, nine hundred ninety-three thousand, six hundred forty-eight".