21151443443021 has 2 divisors, whose sum is σ = 21151443443022. Its totient is φ = 21151443443020.

The previous prime is 21151443442979. The next prime is 21151443443029. The reversal of 21151443443021 is 12034434415112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20437225770025 + 714217672996 = 4520755^2 + 845114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21151443443021 - 2¹⁴ = 21151443426637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21151443443029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575721721510 + 10575721721511.

It is an arithmetic number, because the mean of its divisors is an integer number (10575721721511).

Almost surely, 2^{21151443443021} is an apocalyptic number.

It is an amenable number.

21151443443021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21151443443021 is an equidigital number, since it uses as much as digits as its factorization.

21151443443021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46080, while the sum is 35.

Adding to 21151443443021 its reverse (12034434415112), we get a palindrome (33185877858133).

The spelling of 21151443443021 in words is "twenty-one trillion, one hundred fifty-one billion, four hundred forty-three million, four hundred forty-three thousand, twenty-one".