1212212021 has 4 divisors (see below), whose sum is σ = 1212288492. Its totient is φ = 1212135552.

The previous prime is 1212211991. The next prime is 1212212059. The reversal of 1212212021 is 1202122121.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1202122121 = 9679 ⋅124199.

It can be written as a sum of positive squares in 2 ways, for example, as 1128288100 + 83923921 = 33590^2 + 9161^2 .

It is a cyclic number.

It is not a de Polignac number, because 1212212021 - 2²² = 1208017717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1212211987 and 1212212005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212212321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4586 + ... + 49451.

It is an arithmetic number, because the mean of its divisors is an integer number (303072123).

Almost surely, 2^1212212021 is an apocalyptic number.

It is an amenable number.

1212212021 is a deficient number, since it is larger than the sum of its proper divisors (76471).

1212212021 is an equidigital number, since it uses as much as digits as its factorization.

1212212021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76470.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1212212021 is about 34816.8353099474. The cubic root of 1212212021 is about 1066.2511898273.

Adding to 1212212021 its reverse (1202122121), we get a palindrome (2414334142).

The spelling of 1212212021 in words is "one billion, two hundred twelve million, two hundred twelve thousand, twenty-one".