2501781991 has 2 divisors, whose sum is σ = 2501781992. Its totient is φ = 2501781990.

The previous prime is 2501781937. The next prime is 2501782007. The reversal of 2501781991 is 1991871052.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2501781991 - 2⁹ = 2501781479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2501751991) 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 as a sum of consecutive naturals, namely, 1250890995 + 1250890996.

It is an arithmetic number, because the mean of its divisors is an integer number (1250890996).

Almost surely, 2^2501781991 is an apocalyptic number.

2501781991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2501781991 is an equidigital number, since it uses as much as digits as its factorization.

2501781991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45360, while the sum is 43.

The square root of 2501781991 is about 50017.8167356393. The cubic root of 2501781991 is about 1357.5312028932.

The spelling of 2501781991 in words is "two billion, five hundred one million, seven hundred eighty-one thousand, nine hundred ninety-one".