21221002222001 has 4 divisors (see below), whose sum is σ = 22469296470372. Its totient is φ = 19972707973632.

The previous prime is 21221002221997. The next prime is 21221002222037. The reversal of 21221002222001 is 10022220012212.

It is a happy number.

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 7249965515776 + 13971036706225 = 2692576^2 + 3737785^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221002222001 - 2² = 21221002221997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1248294248353 = 21221002222001 / (2 + 1 + 2 + 2 + 1 + 0 + 0 + 2 + 2 + 2 + 2 + 0 + 0 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221002222051) 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, 624147124160 + ... + 624147124193.

It is an arithmetic number, because the mean of its divisors is an integer number (5617324117593).

Almost surely, 2^{21221002222001} is an apocalyptic number.

It is an amenable number.

21221002222001 is a deficient number, since it is larger than the sum of its proper divisors (1248294248371).

21221002222001 is a wasteful number, since it uses less digits than its factorization.

21221002222001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248294248370.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21221002222001 its reverse (10022220012212), we get a palindrome (31243222234213).

The spelling of 21221002222001 in words is "twenty-one trillion, two hundred twenty-one billion, two million, two hundred twenty-two thousand, one".