81900849 has 16 divisors (see below), whose sum is σ = 121711680. Its totient is φ = 48683520.

The previous prime is 81900829. The next prime is 81900851. The reversal of 81900849 is 94800918.

It is not a de Polignac number, because 81900849 - 2⁸ = 81900593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81900809) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 41292 + ... + 43229.

It is an arithmetic number, because the mean of its divisors is an integer number (7606980).

Almost surely, 2^81900849 is an apocalyptic number.

It is an amenable number.

81900849 is a deficient number, since it is larger than the sum of its proper divisors (39810831).

81900849 is a wasteful number, since it uses less digits than its factorization.

81900849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84560.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 81900849 is about 9049.9087840707. The cubic root of 81900849 is about 434.2729723901.

The spelling of 81900849 in words is "eighty-one million, nine hundred thousand, eight hundred forty-nine".