1665115551 has 24 divisors (see below), whose sum is σ = 2694738384. Its totient is φ = 981884160.

The previous prime is 1665115547. The next prime is 1665115553. The reversal of 1665115551 is 1555115661.

It is a happy number.

It is not a de Polignac number, because 1665115551 - 2² = 1665115547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665115553) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 223626 + ... + 230951.

It is an arithmetic number, because the mean of its divisors is an integer number (112280766).

Almost surely, 2^1665115551 is an apocalyptic number.

1665115551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1665115551 is a deficient number, since it is larger than the sum of its proper divisors (1029622833).

1665115551 is a wasteful number, since it uses less digits than its factorization.

1665115551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454631 (or 454628 counting only the distinct ones).

The product of its digits is 22500, while the sum is 36.

The square root of 1665115551 is about 40805.8274147210. The cubic root of 1665115551 is about 1185.2631771391.

The spelling of 1665115551 in words is "one billion, six hundred sixty-five million, one hundred fifteen thousand, five hundred fifty-one".