2501561891 has 2 divisors, whose sum is σ = 2501561892. Its totient is φ = 2501561890.

The previous prime is 2501561813. The next prime is 2501561911. The reversal of 2501561891 is 1981651052.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2501561891 - 2²⁶ = 2434453027 is a prime.

It is not a weakly prime, because it can be changed into another prime (2501561801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1250780945 + 1250780946.

It is an arithmetic number, because the mean of its divisors is an integer number (1250780946).

Almost surely, 2^2501561891 is an apocalyptic number.

2501561891 is a deficient number, since it is larger than the sum of its proper divisors (1).

2501561891 is an equidigital number, since it uses as much as digits as its factorization.

2501561891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21600, while the sum is 38.

The square root of 2501561891 is about 50015.6164712583. The cubic root of 2501561891 is about 1357.4913910869.

The spelling of 2501561891 in words is "two billion, five hundred one million, five hundred sixty-one thousand, eight hundred ninety-one".