81389002 has 4 divisors (see below), whose sum is σ = 122083506. Its totient is φ = 40694500.

The previous prime is 81388961. The next prime is 81389017. The reversal of 81389002 is 20098318.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 79014321 + 2374681 = 8889^2 + 1541^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20347249 + ... + 20347252.

Almost surely, 2^81389002 is an apocalyptic number.

81389002 is a deficient number, since it is larger than the sum of its proper divisors (40694504).

81389002 is a wasteful number, since it uses less digits than its factorization.

81389002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40694503.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 81389002 is about 9021.5853374005. The cubic root of 81389002 is about 433.3664047081.

The spelling of 81389002 in words is "eighty-one million, three hundred eighty-nine thousand, two".