25161221 has 8 divisors (see below), whose sum is σ = 26100984. Its totient is φ = 24235200.

The previous prime is 25161211. The next prime is 25161223. The reversal of 25161221 is 12216152.

It can be written as a sum of positive squares in 4 ways, for example, as 22944100 + 2217121 = 4790^2 + 1489^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 25161221 - 2¹⁴ = 25144837 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 25161193 and 25161202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25161223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 371 + ... + 7103.

It is an arithmetic number, because the mean of its divisors is an integer number (3262623).

Almost surely, 2^25161221 is an apocalyptic number.

It is an amenable number.

25161221 is a deficient number, since it is larger than the sum of its proper divisors (939763).

25161221 is a wasteful number, since it uses less digits than its factorization.

25161221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6871.

The product of its digits is 240, while the sum is 20.

The square root of 25161221 is about 5016.0961912627. The cubic root of 25161221 is about 293.0289782519.

Adding to 25161221 its reverse (12216152), we get a palindrome (37377373).

The spelling of 25161221 in words is "twenty-five million, one hundred sixty-one thousand, two hundred twenty-one".