21221220101201 has 4 divisors (see below), whose sum is σ = 21226430323812. Its totient is φ = 21216009878592.

The previous prime is 21221220101173. The next prime is 21221220101219. The reversal of 21221220101201 is 10210102212212.

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 7903975582801 + 13317244518400 = 2811401^2 + 3649280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221220101201 - 2²⁶ = 21221152992337 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221220101201.

It is not an unprimeable number, because it can be changed into a prime (21221220101801) 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, 2605105196 + ... + 2605113341.

It is an arithmetic number, because the mean of its divisors is an integer number (5306607580953).

Almost surely, 2^{21221220101201} is an apocalyptic number.

It is an amenable number.

21221220101201 is a deficient number, since it is larger than the sum of its proper divisors (5210222611).

21221220101201 is an equidigital number, since it uses as much as digits as its factorization.

21221220101201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5210222610.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21221220101201 its reverse (10210102212212), we get a palindrome (31431322313413).

The spelling of 21221220101201 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, one hundred one thousand, two hundred one".