25997431821 has 4 divisors (see below), whose sum is σ = 34663242432. Its totient is φ = 17331621212.

The previous prime is 25997431807. The next prime is 25997431847. The reversal of 25997431821 is 12813479952.

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 25997431821 - 2⁹ = 25997431309 is a prime.

It is a super-2 number, since 2×25997431821² (a number of 22 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25997431121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4332905301 + ... + 4332905306.

It is an arithmetic number, because the mean of its divisors is an integer number (8665810608).

Almost surely, 2^25997431821 is an apocalyptic number.

It is an amenable number.

25997431821 is a deficient number, since it is larger than the sum of its proper divisors (8665810611).

25997431821 is an equidigital number, since it uses as much as digits as its factorization.

25997431821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8665810610.

The product of its digits is 1088640, while the sum is 51.

The spelling of 25997431821 in words is "twenty-five billion, nine hundred ninety-seven million, four hundred thirty-one thousand, eight hundred twenty-one".