1321751521 has 2 divisors, whose sum is σ = 1321751522. Its totient is φ = 1321751520.

The previous prime is 1321751503. The next prime is 1321751527. The reversal of 1321751521 is 1251571231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 848906496 + 472845025 = 29136^2 + 21745^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321751521 - 2¹⁵ = 1321718753 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1321751521.

It is not a weakly prime, because it can be changed into another prime (1321751527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660875760 + 660875761.

It is an arithmetic number, because the mean of its divisors is an integer number (660875761).

Almost surely, 2^1321751521 is an apocalyptic number.

It is an amenable number.

1321751521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321751521 is an equidigital number, since it uses as much as digits as its factorization.

1321751521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2100, while the sum is 28.

The square root of 1321751521 is about 36355.9007727769. The cubic root of 1321751521 is about 1097.4462856324.

The spelling of 1321751521 in words is "one billion, three hundred twenty-one million, seven hundred fifty-one thousand, five hundred twenty-one".