81903385 has 8 divisors (see below), whose sum is σ = 100940616. Its totient is φ = 63751680.

The previous prime is 81903383. The next prime is 81903389. The reversal of 81903385 is 58330918.

It can be written as a sum of positive squares in 4 ways, for example, as 3952144 + 77951241 = 1988^2 + 8829^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81903385 - 2¹ = 81903383 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81903383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 221176 + ... + 221545.

It is an arithmetic number, because the mean of its divisors is an integer number (12617577).

Almost surely, 2^81903385 is an apocalyptic number.

It is an amenable number.

81903385 is a deficient number, since it is larger than the sum of its proper divisors (19037231).

81903385 is a wasteful number, since it uses less digits than its factorization.

81903385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442763.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 81903385 is about 9050.0488948955. The cubic root of 81903385 is about 434.2774546590.

The spelling of 81903385 in words is "eighty-one million, nine hundred three thousand, three hundred eighty-five".