81919485 has 16 divisors (see below), whose sum is σ = 145634880. Its totient is φ = 43690320.

The previous prime is 81919477. The next prime is 81919501. The reversal of 81919485 is 58491918.

81919485 is a `hidden beast` number, since 81 + 91 + 9 + 485 = 666.

It is not a de Polignac number, because 81919485 - 2³ = 81919477 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81919485.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 303271 + ... + 303540.

It is an arithmetic number, because the mean of its divisors is an integer number (9102180).

Almost surely, 2^81919485 is an apocalyptic number.

It is an amenable number.

81919485 is a deficient number, since it is larger than the sum of its proper divisors (63715395).

81919485 is a wasteful number, since it uses less digits than its factorization.

81919485 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 606825 (or 606819 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 81919485 is about 9050.9383491437. The cubic root of 81919485 is about 434.3059085458.

The spelling of 81919485 in words is "eighty-one million, nine hundred nineteen thousand, four hundred eighty-five".