1221201010021 has 2 divisors, whose sum is σ = 1221201010022. Its totient is φ = 1221201010020.

The previous prime is 1221201009983. The next prime is 1221201010067. The reversal of 1221201010021 is 1200101021221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1215748812100 + 5452197921 = 1102610^2 + 73839^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221201010021 - 2⁷ = 1221201009893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221201009983 and 1221201010010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221201010091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610600505010 + 610600505011.

It is an arithmetic number, because the mean of its divisors is an integer number (610600505011).

Almost surely, 2^{1221201010021} is an apocalyptic number.

It is an amenable number.

1221201010021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221201010021 is an equidigital number, since it uses as much as digits as its factorization.

1221201010021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 1221201010021 its reverse (1200101021221), we get a palindrome (2421302031242).

The spelling of 1221201010021 in words is "one trillion, two hundred twenty-one billion, two hundred one million, ten thousand, twenty-one".