121220021 has 4 divisors (see below), whose sum is σ = 130544652. Its totient is φ = 111895392.

The previous prime is 121220017. The next prime is 121220023. The reversal of 121220021 is 120022121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120022121 = 8831 ⋅13591.

It can be written as a sum of positive squares in 2 ways, for example, as 37039396 + 84180625 = 6086^2 + 9175^2 .

It is a cyclic number.

It is not a de Polignac number, because 121220021 - 2² = 121220017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 121219984 and 121220011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121220023) 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, 4662296 + ... + 4662321.

It is an arithmetic number, because the mean of its divisors is an integer number (32636163).

Almost surely, 2^121220021 is an apocalyptic number.

It is an amenable number.

121220021 is a deficient number, since it is larger than the sum of its proper divisors (9324631).

121220021 is an equidigital number, since it uses as much as digits as its factorization.

121220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9324630.

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

The square root of 121220021 is about 11009.9964123518. The cubic root of 121220021 is about 494.9083542881.

Adding to 121220021 its reverse (120022121), we get a palindrome (241242142).

The spelling of 121220021 in words is "one hundred twenty-one million, two hundred twenty thousand, twenty-one".