1665055651 has 4 divisors (see below), whose sum is σ = 1902920752. Its totient is φ = 1427190552.

The previous prime is 1665055621. The next prime is 1665055657. The reversal of 1665055651 is 1565505661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1565505661 = 367 ⋅4265683.

It is a cyclic number.

It is not a de Polignac number, because 1665055651 - 2⁷ = 1665055523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665055657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 118932540 + ... + 118932553.

It is an arithmetic number, because the mean of its divisors is an integer number (475730188).

Almost surely, 2^1665055651 is an apocalyptic number.

1665055651 is a deficient number, since it is larger than the sum of its proper divisors (237865101).

1665055651 is an equidigital number, since it uses as much as digits as its factorization.

1665055651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237865100.

The product of its (nonzero) digits is 135000, while the sum is 40.

The square root of 1665055651 is about 40805.0934443238. The cubic root of 1665055651 is about 1185.2489642885.

The spelling of 1665055651 in words is "one billion, six hundred sixty-five million, fifty-five thousand, six hundred fifty-one".