1665253501 has 4 divisors (see below), whose sum is σ = 1665699100. Its totient is φ = 1664807904.

The previous prime is 1665253493. The next prime is 1665253507. The reversal of 1665253501 is 1053525661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1053525661 = 19 ⋅55448719.

It can be written as a sum of positive squares in 2 ways, for example, as 919908900 + 745344601 = 30330^2 + 27301^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665253501 - 2³ = 1665253493 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 (1665253507) 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, 217146 + ... + 224683.

It is an arithmetic number, because the mean of its divisors is an integer number (416424775).

Almost surely, 2^1665253501 is an apocalyptic number.

It is an amenable number.

1665253501 is a deficient number, since it is larger than the sum of its proper divisors (445599).

1665253501 is an equidigital number, since it uses as much as digits as its factorization.

1665253501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445598.

The product of its (nonzero) digits is 27000, while the sum is 34.

The square root of 1665253501 is about 40807.5177020117. The cubic root of 1665253501 is about 1185.2959081089.

The spelling of 1665253501 in words is "one billion, six hundred sixty-five million, two hundred fifty-three thousand, five hundred one".