1525311721 has 2 divisors, whose sum is σ = 1525311722. Its totient is φ = 1525311720.

The previous prime is 1525311709. The next prime is 1525311737. The reversal of 1525311721 is 1271135251.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1500710121 + 24601600 = 38739^2 + 4960^2 .

It is a cyclic number.

It is not a de Polignac number, because 1525311721 - 2¹¹ = 1525309673 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1525311721.

It is not a weakly prime, because it can be changed into another prime (1525311121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 762655860 + 762655861.

It is an arithmetic number, because the mean of its divisors is an integer number (762655861).

Almost surely, 2^1525311721 is an apocalyptic number.

It is an amenable number.

1525311721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1525311721 is an equidigital number, since it uses as much as digits as its factorization.

1525311721 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 1525311721 is about 39055.2393540227. The cubic root of 1525311721 is about 1151.1171805135.

Adding to 1525311721 its reverse (1271135251), we get a palindrome (2796446972).

The spelling of 1525311721 in words is "one billion, five hundred twenty-five million, three hundred eleven thousand, seven hundred twenty-one".