81806002 has 8 divisors (see below), whose sum is σ = 124720812. Its totient is φ = 40232400.

The previous prime is 81805981. The next prime is 81806003. The reversal of 81806002 is 20060818.

It can be written as a sum of positive squares in 2 ways, for example, as 70576801 + 11229201 = 8401^2 + 3351^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81806003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 335149 + ... + 335392.

Almost surely, 2^81806002 is an apocalyptic number.

81806002 is a deficient number, since it is larger than the sum of its proper divisors (42914810).

81806002 is a wasteful number, since it uses less digits than its factorization.

81806002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670604.

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 81806002 is about 9044.6670474927. The cubic root of 81806002 is about 434.1052679871.

The spelling of 81806002 in words is "eighty-one million, eight hundred six thousand, two".