81289930 has 32 divisors (see below), whose sum is σ = 149202000. Its totient is φ = 31882752.

The previous prime is 81289927. The next prime is 81289939. The reversal of 81289930 is 3998218.

It can be written as a sum of positive squares in 8 ways, for example, as 91809 + 81198121 = 303^2 + 9011^2 .

It is not an unprimeable number, because it can be changed into a prime (81289939) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 132304 + ... + 132916.

Almost surely, 2^81289930 is an apocalyptic number.

81289930 is a deficient number, since it is larger than the sum of its proper divisors (67912070).

81289930 is a wasteful number, since it uses less digits than its factorization.

81289930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 858.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 81289930 is about 9016.0928344821. The cubic root of 81289930 is about 433.1904926968.

The spelling of 81289930 in words is "eighty-one million, two hundred eighty-nine thousand, nine hundred thirty".