1001181820 has 24 divisors (see below), whose sum is σ = 2213139600. Its totient is φ = 379395072.

The previous prime is 1001181781. The next prime is 1001181851. The reversal of 1001181820 is 281811001.

It is a junction number, because it is equal to n+sod(n) for n = 1001181791 and 1001181800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1316965 + ... + 1317724.

It is an arithmetic number, because the mean of its divisors is an integer number (92214150).

Almost surely, 2^1001181820 is an apocalyptic number.

1001181820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1001181820 is an abundant number, since it is smaller than the sum of its proper divisors (1211957780).

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

1001181820 is a wasteful number, since it uses less digits than its factorization.

1001181820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2634717 (or 2634715 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 1001181820 is about 31641.4572989298. The cubic root of 1001181820 is about 1000.3937849131.

Adding to 1001181820 its reverse (281811001), we get a palindrome (1282992821).

It can be divided in two parts, 1001181 and 820, that added together give a palindrome (1002001).

The spelling of 1001181820 in words is "one billion, one million, one hundred eighty-one thousand, eight hundred twenty".