25217712521 has 4 divisors (see below), whose sum is σ = 25345721412. Its totient is φ = 25089703632.

The previous prime is 25217712493. The next prime is 25217712547. The reversal of 25217712521 is 12521771252.

It is a happy number.

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 24645546121 + 572166400 = 156989^2 + 23920^2 .

It is a cyclic number.

It is not a de Polignac number, because 25217712521 - 2¹⁴ = 25217696137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25217712581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64004150 + ... + 64004543.

It is an arithmetic number, because the mean of its divisors is an integer number (6336430353).

Almost surely, 2^25217712521 is an apocalyptic number.

It is an amenable number.

25217712521 is a deficient number, since it is larger than the sum of its proper divisors (128008891).

25217712521 is a wasteful number, since it uses less digits than its factorization.

25217712521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128008890.

The product of its digits is 19600, while the sum is 35.

The spelling of 25217712521 in words is "twenty-five billion, two hundred seventeen million, seven hundred twelve thousand, five hundred twenty-one".