1212020021 has 4 divisors (see below), whose sum is σ = 1212103692. Its totient is φ = 1211936352.

The previous prime is 1212020011. The next prime is 1212020027. The reversal of 1212020021 is 1200202121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 485717521 + 726302500 = 22039^2 + 26950^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1212020021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1212019984 and 1212020011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212020027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13880 + ... + 51153.

It is an arithmetic number, because the mean of its divisors is an integer number (303025923).

Almost surely, 2^1212020021 is an apocalyptic number.

It is an amenable number.

1212020021 is a deficient number, since it is larger than the sum of its proper divisors (83671).

1212020021 is an equidigital number, since it uses as much as digits as its factorization.

1212020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83670.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1212020021 is about 34814.0779139704. The cubic root of 1212020021 is about 1066.1948930095.

Adding to 1212020021 its reverse (1200202121), we get a palindrome (2412222142).

The spelling of 1212020021 in words is "one billion, two hundred twelve million, twenty thousand, twenty-one".