21021221002157 has 2 divisors, whose sum is σ = 21021221002158. Its totient is φ = 21021221002156.

The previous prime is 21021221002081. The next prime is 21021221002237. The reversal of 21021221002157 is 75120012212012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15664861588996 + 5356359413161 = 3957886^2 + 2314381^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021221002157 - 2⁸ = 21021221001901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021221052157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510610501078 + 10510610501079.

It is an arithmetic number, because the mean of its divisors is an integer number (10510610501079).

Almost surely, 2^{21021221002157} is an apocalyptic number.

It is an amenable number.

21021221002157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021221002157 is an equidigital number, since it uses as much as digits as its factorization.

21021221002157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1120, while the sum is 26.

Adding to 21021221002157 its reverse (75120012212012), we get a palindrome (96141233214169).

The spelling of 21021221002157 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, two thousand, one hundred fifty-seven".