2551551665 has 16 divisors (see below), whose sum is σ = 3301594128. Its totient is φ = 1881820416.

The previous prime is 2551551659. The next prime is 2551551671. The reversal of 2551551665 is 5661551552.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (2551551659) and next prime (2551551671).

It can be written as a sum of positive squares in 8 ways, for example, as 565868944 + 1985682721 = 23788^2 + 44561^2 .

It is a cyclic number.

It is not a de Polignac number, because 2551551665 - 2⁴ = 2551551649 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27179 + ... + 76431.

It is an arithmetic number, because the mean of its divisors is an integer number (206349633).

Almost surely, 2^2551551665 is an apocalyptic number.

It is an amenable number.

2551551665 is a deficient number, since it is larger than the sum of its proper divisors (750042463).

2551551665 is a wasteful number, since it uses less digits than its factorization.

2551551665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50068.

The product of its digits is 225000, while the sum is 41.

The square root of 2551551665 is about 50512.8861281951. The cubic root of 2551551665 is about 1366.4742604076.

The spelling of 2551551665 in words is "two billion, five hundred fifty-one million, five hundred fifty-one thousand, six hundred sixty-five".