1605641245321 has 27 divisors (see below), whose sum is σ = 1726236879381. Its totient is φ = 1493318242944.

The previous prime is 1605641245303. The next prime is 1605641245331. The reversal of 1605641245321 is 1235421465061.

The square root of 1605641245321 is 1267139.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 36223605625 + 1569417639696 = 190325^2 + 1252764^2 .

It is not a de Polignac number, because 1605641245321 - 2¹¹ = 1605641243273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1605641245301) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1078334545 + ... + 1078336033.

Almost surely, 2^{1605641245321} is an apocalyptic number.

1605641245321 is the 1267139-th square number.

1605641245321 is the 633570-th centered octagonal number.

It is an amenable number.

1605641245321 is a deficient number, since it is larger than the sum of its proper divisors (120595634060).

1605641245321 is an frugal number, since it uses more digits than its factorization.

1605641245321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3098 (or 1549 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 40.

The spelling of 1605641245321 in words is "one trillion, six hundred five billion, six hundred forty-one million, two hundred forty-five thousand, three hundred twenty-one".