81900479 has 4 divisors (see below), whose sum is σ = 82625376. Its totient is φ = 81175584.

The previous prime is 81900473. The next prime is 81900487. The reversal of 81900479 is 97400918.

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

It is not a de Polignac number, because 81900479 - 2⁸ = 81900223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81900473) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 362279 + ... + 362504.

It is an arithmetic number, because the mean of its divisors is an integer number (20656344).

Almost surely, 2^81900479 is an apocalyptic number.

81900479 is a deficient number, since it is larger than the sum of its proper divisors (724897).

81900479 is a wasteful number, since it uses less digits than its factorization.

81900479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724896.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 81900479 is about 9049.8883418526. Note that the first 3 decimals coincide. The cubic root of 81900479 is about 434.2723184236.

The spelling of 81900479 in words is "eighty-one million, nine hundred thousand, four hundred seventy-nine".