1221021002105 has 4 divisors (see below), whose sum is σ = 1465225202532. Its totient is φ = 976816801680.

The previous prime is 1221021002101. The next prime is 1221021002119. The reversal of 1221021002105 is 5012001201221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 806470453369 + 414550548736 = 898037^2 + 643856^2 .

It is not a de Polignac number, because 1221021002105 - 2² = 1221021002101 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221021002101) 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, 122102100206 + ... + 122102100215.

It is an arithmetic number, because the mean of its divisors is an integer number (366306300633).

Almost surely, 2^{1221021002105} is an apocalyptic number.

It is an amenable number.

1221021002105 is a deficient number, since it is larger than the sum of its proper divisors (244204200427).

1221021002105 is an equidigital number, since it uses as much as digits as its factorization.

1221021002105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244204200426.

The product of its (nonzero) digits is 80, while the sum is 17.

Adding to 1221021002105 its reverse (5012001201221), we get a palindrome (6233022203326).

The spelling of 1221021002105 in words is "one trillion, two hundred twenty-one billion, twenty-one million, two thousand, one hundred five".