1820405808 has 360 divisors, whose sum is σ = 6041518080. Its totient is φ = 509483520.

The previous prime is 1820405803. The next prime is 1820405813. The reversal of 1820405808 is 8085040281.

1820405808 is a `hidden beast` number, since 18 + 20 + 40 + 580 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (1820405803) and next prime (1820405813).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (1820405801) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 14333841 + ... + 14333967.

Almost surely, 2^1820405808 is an apocalyptic number.

1820405808 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1820405808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3020759040).

1820405808 is an abundant number, since it is smaller than the sum of its proper divisors (4221112272).

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

1820405808 is a wasteful number, since it uses less digits than its factorization.

1820405808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217 (or 195 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 36.

The square root of 1820405808 is about 42666.2138934309. The cubic root of 1820405808 is about 1221.0198871087.

The spelling of 1820405808 in words is "one billion, eight hundred twenty million, four hundred five thousand, eight hundred eight".