1665120543 has 4 divisors (see below), whose sum is σ = 2220160728. Its totient is φ = 1110080360.

The previous prime is 1665120503. The next prime is 1665120547. The reversal of 1665120543 is 3450215661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1665120543 - 2¹² = 1665116447 is a prime.

It is a super-2 number, since 2×1665120543² = 5545252845441229698, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665120547) 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, 277520088 + ... + 277520093.

It is an arithmetic number, because the mean of its divisors is an integer number (555040182).

Almost surely, 2^1665120543 is an apocalyptic number.

1665120543 is a deficient number, since it is larger than the sum of its proper divisors (555040185).

1665120543 is an equidigital number, since it uses as much as digits as its factorization.

1665120543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555040184.

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 1665120543 is about 40805.8885824093. Note that the first 3 decimals coincide. The cubic root of 1665120543 is about 1185.2643616071.

The spelling of 1665120543 in words is "one billion, six hundred sixty-five million, one hundred twenty thousand, five hundred forty-three".