81388730 has 16 divisors (see below), whose sum is σ = 148983840. Its totient is φ = 32003472.

The previous prime is 81388711. The next prime is 81388751. The reversal of 81388730 is 3788318.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68384 + ... + 69563.

It is an arithmetic number, because the mean of its divisors is an integer number (9311490).

Almost surely, 2^81388730 is an apocalyptic number.

81388730 is a deficient number, since it is larger than the sum of its proper divisors (67595110).

81388730 is a wasteful number, since it uses less digits than its factorization.

81388730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138013.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 81388730 is about 9021.5702624321. The cubic root of 81388730 is about 433.3659219410.

The spelling of 81388730 in words is "eighty-one million, three hundred eighty-eight thousand, seven hundred thirty".