1820506509 has 30 divisors (see below), whose sum is σ = 2768665614. Its totient is φ = 1191808080.

The previous prime is 1820506469. The next prime is 1820506549. The reversal of 1820506509 is 9056050281.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1820506469) and next prime (1820506549).

It can be written as a sum of positive squares in only one way, i.e., 1074397284 + 746109225 = 32778^2 + 27315^2 .

It is not a de Polignac number, because 1820506509 - 2⁸ = 1820506253 is a prime.

It is a super-2 number, since 2×1820506509² = 6628487898622734162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820506549) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 2998884 + ... + 2999490.

Almost surely, 2^1820506509 is an apocalyptic number.

It is an amenable number.

1820506509 is a deficient number, since it is larger than the sum of its proper divisors (948159105).

1820506509 is an frugal number, since it uses more digits than its factorization.

1820506509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1287 (or 671 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 1820506509 is about 42667.3939794781. The cubic root of 1820506509 is about 1221.0424014397.

The spelling of 1820506509 in words is "one billion, eight hundred twenty million, five hundred six thousand, five hundred nine".