1221012021 has 16 divisors (see below), whose sum is σ = 1696000320. Its totient is φ = 780689280.

The previous prime is 1221012007. The next prime is 1221012049. The reversal of 1221012021 is 1202101221.

It is not a de Polignac number, because 1221012021 - 2¹⁰ = 1221010997 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221011988 and 1221012006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221012421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 76870 + ... + 91383.

It is an arithmetic number, because the mean of its divisors is an integer number (106000020).

Almost surely, 2^1221012021 is an apocalyptic number.

It is an amenable number.

1221012021 is a deficient number, since it is larger than the sum of its proper divisors (474988299).

1221012021 is a wasteful number, since it uses less digits than its factorization.

1221012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168356.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 1221012021 is about 34942.9824285220. The cubic root of 1221012021 is about 1068.8251060108.

Adding to 1221012021 its reverse (1202101221), we get a palindrome (2423113242).

The spelling of 1221012021 in words is "one billion, two hundred twenty-one million, twelve thousand, twenty-one".