25993561821 has 4 divisors (see below), whose sum is σ = 34658082432. Its totient is φ = 17329041212.

The previous prime is 25993561807. The next prime is 25993561837. The reversal of 25993561821 is 12816539952.

It is a happy number.

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 25993561821 - 2¹⁰ = 25993560797 is a prime.

It is a super-2 number, since 2×25993561821² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25993561801) 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, 4332260301 + ... + 4332260306.

It is an arithmetic number, because the mean of its divisors is an integer number (8664520608).

Almost surely, 2^25993561821 is an apocalyptic number.

It is an amenable number.

25993561821 is a deficient number, since it is larger than the sum of its proper divisors (8664520611).

25993561821 is an equidigital number, since it uses as much as digits as its factorization.

25993561821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8664520610.

The product of its digits is 1166400, while the sum is 51.

The spelling of 25993561821 in words is "twenty-five billion, nine hundred ninety-three million, five hundred sixty-one thousand, eight hundred twenty-one".