25839816821 has 16 divisors (see below), whose sum is σ = 33476688000. Its totient is φ = 19368652608.

The previous prime is 25839816817. The next prime is 25839816841. The reversal of 25839816821 is 12861893852.

It is a cyclic number.

It is not a de Polignac number, because 25839816821 - 2² = 25839816817 is a prime.

It is a super-3 number, since 3×25839816821³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25839816841) 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 in 15 ways as a sum of consecutive naturals, for example, 7470746 + ... + 7474203.

It is an arithmetic number, because the mean of its divisors is an integer number (2092293000).

Almost surely, 2^25839816821 is an apocalyptic number.

It is an amenable number.

25839816821 is a deficient number, since it is larger than the sum of its proper divisors (7636871179).

25839816821 is a wasteful number, since it uses less digits than its factorization.

25839816821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14944988.

The product of its digits is 1658880, while the sum is 53.

The spelling of 25839816821 in words is "twenty-five billion, eight hundred thirty-nine million, eight hundred sixteen thousand, eight hundred twenty-one".