1021552215521 has 2 divisors, whose sum is σ = 1021552215522. Its totient is φ = 1021552215520.

The previous prime is 1021552215493. The next prime is 1021552215547. The reversal of 1021552215521 is 1255122551201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 762410131921 + 259142083600 = 873161^2 + 509060^2 .

It is an emirp because it is prime and its reverse (1255122551201) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1021552215521 is a prime.

It is not a weakly prime, because it can be changed into another prime (1021552215421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510776107760 + 510776107761.

It is an arithmetic number, because the mean of its divisors is an integer number (510776107761).

Almost surely, 2^{1021552215521} is an apocalyptic number.

It is an amenable number.

1021552215521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021552215521 is an equidigital number, since it uses as much as digits as its factorization.

1021552215521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10000, while the sum is 32.

Adding to 1021552215521 its reverse (1255122551201), we get a palindrome (2276674766722).

The spelling of 1021552215521 in words is "one trillion, twenty-one billion, five hundred fifty-two million, two hundred fifteen thousand, five hundred twenty-one".