1821549505 has 4 divisors (see below), whose sum is σ = 2185859412. Its totient is φ = 1457239600.

The previous prime is 1821549503. The next prime is 1821549581. The reversal of 1821549505 is 5059451281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5059451281 = 20327 ⋅248903.

It can be written as a sum of positive squares in 2 ways, for example, as 1404450576 + 417098929 = 37476^2 + 20423^2 .

It is not a de Polignac number, because 1821549505 - 2¹ = 1821549503 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1821549503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182154946 + ... + 182154955.

It is an arithmetic number, because the mean of its divisors is an integer number (546464853).

Almost surely, 2^1821549505 is an apocalyptic number.

It is an amenable number.

1821549505 is a deficient number, since it is larger than the sum of its proper divisors (364309907).

1821549505 is an equidigital number, since it uses as much as digits as its factorization.

1821549505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364309906.

The product of its (nonzero) digits is 72000, while the sum is 40.

The square root of 1821549505 is about 42679.6146304064. The cubic root of 1821549505 is about 1221.2755415394.

The spelling of 1821549505 in words is "one billion, eight hundred twenty-one million, five hundred forty-nine thousand, five hundred five".