1665397855 has 8 divisors (see below), whose sum is σ = 2180157264. Its totient is φ = 1211198400.

The previous prime is 1665397849. The next prime is 1665397889. The reversal of 1665397855 is 5587935661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1665397855 - 2¹¹ = 1665395807 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (55), and also a Moran number because the ratio is a prime number: 30279961 = 1665397855 / (1 + 6 + 6 + 5 + 3 + 9 + 7 + 8 + 5 + 5).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1665397796 and 1665397805.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15139926 + ... + 15140035.

It is an arithmetic number, because the mean of its divisors is an integer number (272519658).

Almost surely, 2^1665397855 is an apocalyptic number.

1665397855 is a deficient number, since it is larger than the sum of its proper divisors (514759409).

1665397855 is a wasteful number, since it uses less digits than its factorization.

1665397855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30279977.

The product of its digits is 6804000, while the sum is 55.

The square root of 1665397855 is about 40809.2863819009. The cubic root of 1665397855 is about 1185.3301566005.

The spelling of 1665397855 in words is "one billion, six hundred sixty-five million, three hundred ninety-seven thousand, eight hundred fifty-five".