81389581250 has 24 divisors (see below), whose sum is σ = 152595709812. Its totient is φ = 32555830000.

The previous prime is 81389581219. The next prime is 81389581261. The reversal of 81389581250 is 5218598318.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 122965921 + 81266615329 = 11089^2 + 285073^2 .

It is a Harshad number since it is a multiple of its sum of digits (50).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6504917 + ... + 6517416.

Almost surely, 2^81389581250 is an apocalyptic number.

81389581250 is a deficient number, since it is larger than the sum of its proper divisors (71206128562).

81389581250 is an equidigital number, since it uses as much as digits as its factorization.

81389581250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13022360 (or 13022340 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 50.

The spelling of 81389581250 in words is "eighty-one billion, three hundred eighty-nine million, five hundred eighty-one thousand, two hundred fifty".