1221020100021 has 32 divisors (see below), whose sum is σ = 1649089403136. Its totient is φ = 803534400000.

The previous prime is 1221020099993. The next prime is 1221020100037. The reversal of 1221020100021 is 1200010201221.

It is not a de Polignac number, because 1221020100021 - 2¹⁹ = 1221019575733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221020300021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 149502480 + ... + 149510646.

It is an arithmetic number, because the mean of its divisors is an integer number (51534043848).

Almost surely, 2^{1221020100021} is an apocalyptic number.

It is an amenable number.

1221020100021 is a deficient number, since it is larger than the sum of its proper divisors (428069303115).

1221020100021 is a wasteful number, since it uses less digits than its factorization.

1221020100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9693.

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

Adding to 1221020100021 its reverse (1200010201221), we get a palindrome (2421030301242).

The spelling of 1221020100021 in words is "one trillion, two hundred twenty-one billion, twenty million, one hundred thousand, twenty-one".