2778521 has 2 divisors, whose sum is σ = 2778522. Its totient is φ = 2778520.

The previous prime is 2778481. The next prime is 2778527. The reversal of 2778521 is 1258772.

2778521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2758921 + 19600 = 1661^2 + 140^2 .

It is a cyclic number.

It is not a de Polignac number, because 2778521 - 2¹⁸ = 2516377 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (2778527) 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, 1389260 + 1389261.

It is an arithmetic number, because the mean of its divisors is an integer number (1389261).

2^2778521 is an apocalyptic number.

It is an amenable number.

2778521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2778521 is an equidigital number, since it uses as much as digits as its factorization.

2778521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7840, while the sum is 32.

The square root of 2778521 is about 1666.8896184211. The cubic root of 2778521 is about 140.5846469236.

The spelling of 2778521 in words is "two million, seven hundred seventy-eight thousand, five hundred twenty-one".