25206821 has 4 divisors (see below), whose sum is σ = 25367532. Its totient is φ = 25046112.

The previous prime is 25206803. The next prime is 25206871. The reversal of 25206821 is 12860252.

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 14546596 + 10660225 = 3814^2 + 3265^2 .

It is a cyclic number.

It is not a de Polignac number, because 25206821 - 2²² = 21012517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25206871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80120 + ... + 80433.

It is an arithmetic number, because the mean of its divisors is an integer number (6341883).

Almost surely, 2^25206821 is an apocalyptic number.

It is an amenable number.

25206821 is a deficient number, since it is larger than the sum of its proper divisors (160711).

25206821 is a wasteful number, since it uses less digits than its factorization.

25206821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160710.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 25206821 is about 5020.6395010994. The cubic root of 25206821 is about 293.2058914657.

The spelling of 25206821 in words is "twenty-five million, two hundred six thousand, eight hundred twenty-one".