81781748 has 12 divisors (see below), whose sum is σ = 144930240. Its totient is φ = 40373112.

The previous prime is 81781727. The next prime is 81781783. The reversal of 81781748 is 84718718.

It is a hoax number, since the sum of its digits (44) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 81781699 and 81781708.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129086 + ... + 129717.

It is an arithmetic number, because the mean of its divisors is an integer number (12077520).

Almost surely, 2^81781748 is an apocalyptic number.

It is an amenable number.

81781748 is a deficient number, since it is larger than the sum of its proper divisors (63148492).

81781748 is a wasteful number, since it uses less digits than its factorization.

81781748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258886 (or 258884 counting only the distinct ones).

The product of its digits is 100352, while the sum is 44.

The square root of 81781748 is about 9043.3261580018. The cubic root of 81781748 is about 434.0623622930.

The spelling of 81781748 in words is "eighty-one million, seven hundred eighty-one thousand, seven hundred forty-eight".