81318740 has 12 divisors (see below), whose sum is σ = 170769396. Its totient is φ = 32527488.

The previous prime is 81318709. The next prime is 81318779. The reversal of 81318740 is 4781318.

It can be written as a sum of positive squares in 2 ways, for example, as 63712324 + 17606416 = 7982^2 + 4196^2 .

It is a super-2 number, since 2×81318740² = 13225474950375200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81318697 and 81318706.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2032949 + ... + 2032988.

It is an arithmetic number, because the mean of its divisors is an integer number (14230783).

Almost surely, 2^81318740 is an apocalyptic number.

It is an amenable number.

81318740 is an abundant number, since it is smaller than the sum of its proper divisors (89450656).

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

81318740 is a wasteful number, since it uses less digits than its factorization.

81318740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4065946 (or 4065944 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 81318740 is about 9017.6903916690. The cubic root of 81318740 is about 433.2416623968.

The spelling of 81318740 in words is "eighty-one million, three hundred eighteen thousand, seven hundred forty".