25851720397 has 4 divisors (see below), whose sum is σ = 27212337280. Its totient is φ = 24491103516.

The previous prime is 25851720383. The next prime is 25851720467. The reversal of 25851720397 is 79302715852.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 25851720397 - 2⁷ = 25851720269 is a prime.

It is a super-2 number, since 2×25851720397² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 25851720397.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25851720337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 680308413 + ... + 680308450.

It is an arithmetic number, because the mean of its divisors is an integer number (6803084320).

Almost surely, 2^25851720397 is an apocalyptic number.

It is an amenable number.

25851720397 is a deficient number, since it is larger than the sum of its proper divisors (1360616883).

25851720397 is a wasteful number, since it uses less digits than its factorization.

25851720397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1360616882.

The product of its (nonzero) digits is 1058400, while the sum is 49.

The spelling of 25851720397 in words is "twenty-five billion, eight hundred fifty-one million, seven hundred twenty thousand, three hundred ninety-seven".