81520789 has 8 divisors (see below), whose sum is σ = 93242880. Its totient is φ = 69817776.

The previous prime is 81520787. The next prime is 81520801. The reversal of 81520789 is 98702518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81520789 - 2¹ = 81520787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81520781) 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, 6027 + ... + 14119.

It is an arithmetic number, because the mean of its divisors is an integer number (11655360).

Almost surely, 2^81520789 is an apocalyptic number.

It is an amenable number.

81520789 is a deficient number, since it is larger than the sum of its proper divisors (11722091).

81520789 is a wasteful number, since it uses less digits than its factorization.

81520789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9539.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 81520789 is about 9028.8863654384. The cubic root of 81520789 is about 433.6001842890.

The spelling of 81520789 in words is "eighty-one million, five hundred twenty thousand, seven hundred eighty-nine".