81908902 has 4 divisors (see below), whose sum is σ = 122863356. Its totient is φ = 40954450.

The previous prime is 81908899. The next prime is 81908917. The reversal of 81908902 is 20980918.

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

It is a congruent number.

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, 20477224 + ... + 20477227.

It is an arithmetic number, because the mean of its divisors is an integer number (30715839).

Almost surely, 2^81908902 is an apocalyptic number.

81908902 is a deficient number, since it is larger than the sum of its proper divisors (40954454).

81908902 is a wasteful number, since it uses less digits than its factorization.

81908902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40954453.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 81908902 is about 9050.3536947459. The cubic root of 81908902 is about 434.2872053953.

The spelling of 81908902 in words is "eighty-one million, nine hundred eight thousand, nine hundred two".