1643520325 has 6 divisors (see below), whose sum is σ = 2037965234. Its totient is φ = 1314816240.

The previous prime is 1643520323. The next prime is 1643520341. The reversal of 1643520325 is 5230253461.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 364313569 + 1279206756 = 19087^2 + 35766^2 .

It is not a de Polignac number, because 1643520325 - 2¹ = 1643520323 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643520323) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32870382 + ... + 32870431.

Almost surely, 2^1643520325 is an apocalyptic number.

It is an amenable number.

1643520325 is a deficient number, since it is larger than the sum of its proper divisors (394444909).

1643520325 is an equidigital number, since it uses as much as digits as its factorization.

1643520325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65740823 (or 65740818 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 1643520325 is about 40540.3542781757. The cubic root of 1643520325 is about 1180.1168908910.

Adding to 1643520325 its reverse (5230253461), we get a palindrome (6873773786).

The spelling of 1643520325 in words is "one billion, six hundred forty-three million, five hundred twenty thousand, three hundred twenty-five".