1211242021 has 4 divisors (see below), whose sum is σ = 1321354944. Its totient is φ = 1101129100.

The previous prime is 1211241989. The next prime is 1211242051. The reversal of 1211242021 is 1202421121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1211242021 - 2⁵ = 1211241989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211241986 and 1211242004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211242051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55056445 + ... + 55056466.

It is an arithmetic number, because the mean of its divisors is an integer number (330338736).

Almost surely, 2^1211242021 is an apocalyptic number.

1211242021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1211242021 is a deficient number, since it is larger than the sum of its proper divisors (110112923).

1211242021 is a wasteful number, since it uses less digits than its factorization.

1211242021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110112922.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 1211242021 is about 34802.9024795347. The cubic root of 1211242021 is about 1065.9667127369.

Adding to 1211242021 its reverse (1202421121), we get a palindrome (2413663142).

Subtracting from 1211242021 its reverse (1202421121), we obtain a square (8820900 = 2970²).

The spelling of 1211242021 in words is "one billion, two hundred eleven million, two hundred forty-two thousand, twenty-one".