2051661001 has 4 divisors (see below), whose sum is σ = 2209481092. Its totient is φ = 1893840912.

The previous prime is 2051660987. The next prime is 2051661023. The reversal of 2051661001 is 1001661502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1001661502 = 2 ⋅500830751.

It can be written as a sum of positive squares in 2 ways, for example, as 932691600 + 1118969401 = 30540^2 + 33451^2 .

It is a cyclic number.

It is not a de Polignac number, because 2051661001 - 2⁵ = 2051660969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2051667001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78910026 + ... + 78910051.

It is an arithmetic number, because the mean of its divisors is an integer number (552370273).

Almost surely, 2^2051661001 is an apocalyptic number.

It is an amenable number.

2051661001 is a deficient number, since it is larger than the sum of its proper divisors (157820091).

2051661001 is a wasteful number, since it uses less digits than its factorization.

2051661001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157820090.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 2051661001 is about 45295.2646642008. The cubic root of 2051661001 is about 1270.6770938417.

The spelling of 2051661001 in words is "two billion, fifty-one million, six hundred sixty-one thousand, one".