1643410521 has 9 divisors (see below), whose sum is σ = 2373990879. Its totient is φ = 1095525936.

The previous prime is 1643410511. The next prime is 1643410523. The reversal of 1643410521 is 1250143461.

It is a happy number.

The square root of 1643410521 is 40539.

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

1643410521 is a `hidden beast` number, since 1 + 643 + 4 + 10 + 5 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 867008025 + 776402496 = 29445^2 + 27864^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1643410521 - 2⁷ = 1643410393 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1643410523) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 114861 + ... + 128373.

Almost surely, 2^1643410521 is an apocalyptic number.

1643410521 is the 40539-th square number.

1643410521 is the 20270-th centered octagonal number.

It is an amenable number.

1643410521 is a deficient number, since it is larger than the sum of its proper divisors (730580358).

1643410521 is an frugal number, since it uses more digits than its factorization.

1643410521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27032 (or 13516 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The cubic root of 1643410521 is about 1180.0906090050.

Adding to 1643410521 its reverse (1250143461), we get a palindrome (2893553982).

It can be divided in two parts, 1643 and 410521, that added together give a square (412164 = 642²).

The spelling of 1643410521 in words is "one billion, six hundred forty-three million, four hundred ten thousand, five hundred twenty-one".