2505991 has 2 divisors, whose sum is σ = 2505992. Its totient is φ = 2505990.

The previous prime is 2505989. The next prime is 2506003. The reversal of 2505991 is 1995052.

2505991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2505991 - 2¹ = 2505989 is a prime.

Together with 2505989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2505901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1252995 + 1252996.

It is an arithmetic number, because the mean of its divisors is an integer number (1252996).

2^2505991 is an apocalyptic number.

2505991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2505991 is an equidigital number, since it uses as much as digits as its factorization.

2505991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4050, while the sum is 31.

The square root of 2505991 is about 1583.0322169811. The cubic root of 2505991 is about 135.8292081835.

It can be divided in two parts, 250 and 5991, that added together give a square (6241 = 79²).

The spelling of 2505991 in words is "two million, five hundred five thousand, nine hundred ninety-one".