25697821 has 2 divisors, whose sum is σ = 25697822. Its totient is φ = 25697820.

The previous prime is 25697813. The next prime is 25697827. The reversal of 25697821 is 12879652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25613721 + 84100 = 5061^2 + 290^2 .

It is a cyclic number.

It is not a de Polignac number, because 25697821 - 2³ = 25697813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25697827) 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, 12848910 + 12848911.

It is an arithmetic number, because the mean of its divisors is an integer number (12848911).

Almost surely, 2^25697821 is an apocalyptic number.

It is an amenable number.

25697821 is a deficient number, since it is larger than the sum of its proper divisors (1).

25697821 is an equidigital number, since it uses as much as digits as its factorization.

25697821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 40.

The square root of 25697821 is about 5069.3018256955. The cubic root of 25697821 is about 295.0974340608.

The spelling of 25697821 in words is "twenty-five million, six hundred ninety-seven thousand, eight hundred twenty-one".