25520405821 has 4 divisors (see below), whose sum is σ = 25575525952. Its totient is φ = 25465285692.

The previous prime is 25520405791. The next prime is 25520405839. The reversal of 25520405821 is 12850402552.

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 25520405821 - 2¹¹ = 25520403773 is a prime.

It is a super-2 number, since 2×25520405821² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25520405851) 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, 27559371 + ... + 27560296.

It is an arithmetic number, because the mean of its divisors is an integer number (6393881488).

Almost surely, 2^25520405821 is an apocalyptic number.

It is an amenable number.

25520405821 is a deficient number, since it is larger than the sum of its proper divisors (55120131).

25520405821 is an equidigital number, since it uses as much as digits as its factorization.

25520405821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55120130.

The product of its (nonzero) digits is 32000, while the sum is 34.

The spelling of 25520405821 in words is "twenty-five billion, five hundred twenty million, four hundred five thousand, eight hundred twenty-one".