1645520663 has 4 divisors (see below), whose sum is σ = 1645723608. Its totient is φ = 1645317720.

The previous prime is 1645520621. The next prime is 1645520699. The reversal of 1645520663 is 3660255461.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3660255461 = 19231 ⋅190331.

It is a cyclic number.

It is not a de Polignac number, because 1645520663 - 2¹⁴ = 1645504279 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 (1645522663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88781 + ... + 105702.

It is an arithmetic number, because the mean of its divisors is an integer number (411430902).

Almost surely, 2^1645520663 is an apocalyptic number.

1645520663 is a deficient number, since it is larger than the sum of its proper divisors (202945).

1645520663 is an equidigital number, since it uses as much as digits as its factorization.

1645520663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202944.

The product of its (nonzero) digits is 129600, while the sum is 38.

The square root of 1645520663 is about 40565.0177246356. The cubic root of 1645520663 is about 1180.5954724575.

The spelling of 1645520663 in words is "one billion, six hundred forty-five million, five hundred twenty thousand, six hundred sixty-three".