81747740 has 24 divisors (see below), whose sum is σ = 172171440. Its totient is φ = 32603648.

The previous prime is 81747739. The next prime is 81747751. The reversal of 81747740 is 4774718.

It is a junction number, because it is equal to n+sod(n) for n = 81747694 and 81747703.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1271 + ... + 12849.

It is an arithmetic number, because the mean of its divisors is an integer number (7173810).

Almost surely, 2^81747740 is an apocalyptic number.

It is an amenable number.

81747740 is an abundant number, since it is smaller than the sum of its proper divisors (90423700).

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

81747740 is a wasteful number, since it uses less digits than its factorization.

81747740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11941 (or 11939 counting only the distinct ones).

The product of its (nonzero) digits is 43904, while the sum is 38.

The square root of 81747740 is about 9041.4456808632. The cubic root of 81747740 is about 434.0021873363.

The spelling of 81747740 in words is "eighty-one million, seven hundred forty-seven thousand, seven hundred forty".