1705221521 has 2 divisors, whose sum is σ = 1705221522. Its totient is φ = 1705221520.

The previous prime is 1705221517. The next prime is 1705221563. The reversal of 1705221521 is 1251225071.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1307617921 + 397603600 = 36161^2 + 19940^2 .

It is an emirp because it is prime and its reverse (1251225071) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1705221521 - 2² = 1705221517 is a prime.

It is not a weakly prime, because it can be changed into another prime (1705221571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 852610760 + 852610761.

It is an arithmetic number, because the mean of its divisors is an integer number (852610761).

Almost surely, 2^1705221521 is an apocalyptic number.

It is an amenable number.

1705221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1705221521 is an equidigital number, since it uses as much as digits as its factorization.

1705221521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1400, while the sum is 26.

The square root of 1705221521 is about 41294.3279519113. The cubic root of 1705221521 is about 1194.7038641093.

Adding to 1705221521 its reverse (1251225071), we get a palindrome (2956446592).

The spelling of 1705221521 in words is "one billion, seven hundred five million, two hundred twenty-one thousand, five hundred twenty-one".