1021551127721 has 2 divisors, whose sum is σ = 1021551127722. Its totient is φ = 1021551127720.

The previous prime is 1021551127661. The next prime is 1021551127757. The reversal of 1021551127721 is 1277211551201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 978494877721 + 43056250000 = 989189^2 + 207500^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021551127721 - 2⁶ = 1021551127657 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1021551127781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510775563860 + 510775563861.

It is an arithmetic number, because the mean of its divisors is an integer number (510775563861).

Almost surely, 2^{1021551127721} is an apocalyptic number.

It is an amenable number.

1021551127721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021551127721 is an equidigital number, since it uses as much as digits as its factorization.

1021551127721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9800, while the sum is 35.

Adding to 1021551127721 its reverse (1277211551201), we get a palindrome (2298762678922).

The spelling of 1021551127721 in words is "one trillion, twenty-one billion, five hundred fifty-one million, one hundred twenty-seven thousand, seven hundred twenty-one".