2551899661 has 4 divisors (see below), whose sum is σ = 2552226300. Its totient is φ = 2551573024.

The previous prime is 2551899653. The next prime is 2551899667. The reversal of 2551899661 is 1669981552.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1865721636 + 686178025 = 43194^2 + 26195^2 .

It is a cyclic number.

It is not a de Polignac number, because 2551899661 - 2³ = 2551899653 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2551899599 and 2551899608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2551899667) 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, 151306 + ... + 167323.

It is an arithmetic number, because the mean of its divisors is an integer number (638056575).

Almost surely, 2^2551899661 is an apocalyptic number.

It is an amenable number.

2551899661 is a deficient number, since it is larger than the sum of its proper divisors (326639).

2551899661 is an equidigital number, since it uses as much as digits as its factorization.

2551899661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326638.

The product of its digits is 1166400, while the sum is 52.

The square root of 2551899661 is about 50516.3306367357. The cubic root of 2551899661 is about 1366.5363802497.

The spelling of 2551899661 in words is "two billion, five hundred fifty-one million, eight hundred ninety-nine thousand, six hundred sixty-one".