2566739561 has 2 divisors, whose sum is σ = 2566739562. Its totient is φ = 2566739560.

The previous prime is 2566739477. The next prime is 2566739587. The reversal of 2566739561 is 1659376652.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1870043536 + 696696025 = 43244^2 + 26395^2 .

It is a cyclic number.

It is not a de Polignac number, because 2566739561 - 2¹⁴ = 2566723177 is a prime.

It is not a weakly prime, because it can be changed into another prime (2566739261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1283369780 + 1283369781.

It is an arithmetic number, because the mean of its divisors is an integer number (1283369781).

Almost surely, 2^2566739561 is an apocalyptic number.

It is an amenable number.

2566739561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2566739561 is an equidigital number, since it uses as much as digits as its factorization.

2566739561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2041200, while the sum is 50.

The square root of 2566739561 is about 50662.9999210469. Note that the first 4 decimals coincide. The cubic root of 2566739561 is about 1369.1801728296.

The spelling of 2566739561 in words is "two billion, five hundred sixty-six million, seven hundred thirty-nine thousand, five hundred sixty-one".