25919220821 has 4 divisors (see below), whose sum is σ = 27913007052. Its totient is φ = 23925434592.

The previous prime is 25919220809. The next prime is 25919220829. The reversal of 25919220821 is 12802291952.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17300140900 + 8619079921 = 131530^2 + 92839^2 .

It is a cyclic number.

It is not a de Polignac number, because 25919220821 - 2¹⁸ = 25918958677 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25919220829) 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, 996893096 + ... + 996893121.

It is an arithmetic number, because the mean of its divisors is an integer number (6978251763).

Almost surely, 2^25919220821 is an apocalyptic number.

It is an amenable number.

25919220821 is a deficient number, since it is larger than the sum of its proper divisors (1993786231).

25919220821 is a wasteful number, since it uses less digits than its factorization.

25919220821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1993786230.

The product of its (nonzero) digits is 51840, while the sum is 41.

The spelling of 25919220821 in words is "twenty-five billion, nine hundred nineteen million, two hundred twenty thousand, eight hundred twenty-one".