1820181820 has 24 divisors (see below), whose sum is σ = 3988573344. Its totient is φ = 696417216.

The previous prime is 1820181799. The next prime is 1820181827. The reversal of 1820181820 is 281810281.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820181827) 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, 1977999 + ... + 1978918.

It is an arithmetic number, because the mean of its divisors is an integer number (166190556).

Almost surely, 2^1820181820 is an apocalyptic number.

1820181820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1820181820 is an abundant number, since it is smaller than the sum of its proper divisors (2168391524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1820181820 is a wasteful number, since it uses less digits than its factorization.

1820181820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3956949 (or 3956947 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 31.

The square root of 1820181820 is about 42663.5889254526. The cubic root of 1820181820 is about 1220.9698057809.

The spelling of 1820181820 in words is "one billion, eight hundred twenty million, one hundred eighty-one thousand, eight hundred twenty".