1221201021 has 16 divisors (see below), whose sum is σ = 1675415744. Its totient is φ = 790642944.

The previous prime is 1221201019. The next prime is 1221201083. The reversal of 1221201021 is 1201021221.

It is not a de Polignac number, because 1221201021 - 2¹ = 1221201019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221200988 and 1221201006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221201221) 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, 50661 + ... + 70773.

It is an arithmetic number, because the mean of its divisors is an integer number (104713484).

Almost surely, 2^1221201021 is an apocalyptic number.

It is an amenable number.

1221201021 is a deficient number, since it is larger than the sum of its proper divisors (454214723).

1221201021 is a wasteful number, since it uses less digits than its factorization.

1221201021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20700.

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

The square root of 1221201021 is about 34945.6867295522. The cubic root of 1221201021 is about 1068.8802508468.

Adding to 1221201021 its reverse (1201021221), we get a palindrome (2422222242).

The spelling of 1221201021 in words is "one billion, two hundred twenty-one million, two hundred one thousand, twenty-one".