81906802 has 4 divisors (see below), whose sum is σ = 122860206. Its totient is φ = 40953400.

The previous prime is 81906719. The next prime is 81906823. The reversal of 81906802 is 20860918.

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., 47320641 + 34586161 = 6879^2 + 5881^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20476699 + ... + 20476702.

Almost surely, 2^81906802 is an apocalyptic number.

81906802 is a deficient number, since it is larger than the sum of its proper divisors (40953404).

81906802 is a wasteful number, since it uses less digits than its factorization.

81906802 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40953403.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 81906802 is about 9050.2376764370. The cubic root of 81906802 is about 434.2834939105.

The spelling of 81906802 in words is "eighty-one million, nine hundred six thousand, eight hundred two".