21221001811001 has 2 divisors, whose sum is σ = 21221001811002. Its totient is φ = 21221001811000.

The previous prime is 21221001810961. The next prime is 21221001811039. The reversal of 21221001811001 is 10011810012212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18717088005625 + 2503913805376 = 4326325^2 + 1582376^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221001811001 - 2⁶ = 21221001810937 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221001811201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610500905500 + 10610500905501.

It is an arithmetic number, because the mean of its divisors is an integer number (10610500905501).

Almost surely, 2^{21221001811001} is an apocalyptic number.

It is an amenable number.

21221001811001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221001811001 is an equidigital number, since it uses as much as digits as its factorization.

21221001811001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 21221001811001 its reverse (10011810012212), we get a palindrome (31232811823213).

The spelling of 21221001811001 in words is "twenty-one trillion, two hundred twenty-one billion, one million, eight hundred eleven thousand, one".