25778021 has 2 divisors, whose sum is σ = 25778022. Its totient is φ = 25778020.

The previous prime is 25777993. The next prime is 25778029. The reversal of 25778021 is 12087752.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 5428900 = 4511^2 + 2330^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25778021 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25778029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12889010 + 12889011.

It is an arithmetic number, because the mean of its divisors is an integer number (12889011).

Almost surely, 2^25778021 is an apocalyptic number.

It is an amenable number.

25778021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25778021 is an equidigital number, since it uses as much as digits as its factorization.

25778021 is an odious number, because the sum of its binary digits is odd.

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

The square root of 25778021 is about 5077.2060230012. The cubic root of 25778021 is about 295.4041038536.

The spelling of 25778021 in words is "twenty-five million, seven hundred seventy-eight thousand, twenty-one".