1221021020021 has 4 divisors (see below), whose sum is σ = 1332022930944. Its totient is φ = 1110019109100.

The previous prime is 1221021020017. The next prime is 1221021020059. The reversal of 1221021020021 is 1200201201221.

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 not a de Polignac number, because 1221021020021 - 2² = 1221021020017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221021019978 and 1221021020005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221021020081) 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, 55500955445 + ... + 55500955466.

It is an arithmetic number, because the mean of its divisors is an integer number (333005732736).

Almost surely, 2^{1221021020021} is an apocalyptic number.

1221021020021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221021020021 is a deficient number, since it is larger than the sum of its proper divisors (111001910923).

1221021020021 is a wasteful number, since it uses less digits than its factorization.

1221021020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111001910922.

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

Adding to 1221021020021 its reverse (1200201201221), we get a palindrome (2421222221242).

The spelling of 1221021020021 in words is "one trillion, two hundred twenty-one billion, twenty-one million, twenty thousand, twenty-one".