1212100020 has 72 divisors (see below), whose sum is σ = 3776094504. Its totient is φ = 314489088.

The previous prime is 1212100009. The next prime is 1212100027. The reversal of 1212100020 is 200012121.

It can be written as a sum of positive squares in 4 ways, for example, as 420578064 + 791521956 = 20508^2 + 28134^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 1212099975 and 1212100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212100027) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 84339 + ... + 97658.

It is an arithmetic number, because the mean of its divisors is an integer number (52445757).

Almost surely, 2^1212100020 is an apocalyptic number.

1212100020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1212100020 is an abundant number, since it is smaller than the sum of its proper divisors (2563994484).

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

1212100020 is a wasteful number, since it uses less digits than its factorization.

1212100020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182049 (or 182044 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1212100020 is about 34815.2268411395. The cubic root of 1212100020 is about 1066.2183504462.

Adding to 1212100020 its reverse (200012121), we get a palindrome (1412112141).

The spelling of 1212100020 in words is "one billion, two hundred twelve million, one hundred thousand, twenty".