21051222001 has 2 divisors, whose sum is σ = 21051222002. Its totient is φ = 21051222000.

The previous prime is 21051221929. The next prime is 21051222097. The reversal of 21051222001 is 10022215012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13311621376 + 7739600625 = 115376^2 + 87975^2 .

It is a cyclic number.

It is not a de Polignac number, because 21051222001 - 2⁹ = 21051221489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21051222701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525611000 + 10525611001.

It is an arithmetic number, because the mean of its divisors is an integer number (10525611001).

Almost surely, 2^21051222001 is an apocalyptic number.

It is an amenable number.

21051222001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21051222001 is an equidigital number, since it uses as much as digits as its factorization.

21051222001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 21051222001 its reverse (10022215012), we get a palindrome (31073437013).

The spelling of 21051222001 in words is "twenty-one billion, fifty-one million, two hundred twenty-two thousand, one".