25517421 has 6 divisors (see below), whose sum is σ = 36858510. Its totient is φ = 17011608.

The previous prime is 25517417. The next prime is 25517423. The reversal of 25517421 is 12471552.

It can be written as a sum of positive squares in only one way, i.e., 19900521 + 5616900 = 4461^2 + 2370^2 .

It is not a de Polignac number, because 25517421 - 2² = 25517417 is a prime.

It is a super-2 number, since 2×25517421² = 1302277548982482, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25517423) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1417626 + ... + 1417643.

It is an arithmetic number, because the mean of its divisors is an integer number (6143085).

Almost surely, 2^25517421 is an apocalyptic number.

It is an amenable number.

25517421 is a deficient number, since it is larger than the sum of its proper divisors (11341089).

25517421 is a wasteful number, since it uses less digits than its factorization.

25517421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2835275 (or 2835272 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 25517421 is about 5051.4771107073. The cubic root of 25517421 is about 294.4052789118.

Adding to 25517421 its reverse (12471552), we get a palindrome (37988973).

The spelling of 25517421 in words is "twenty-five million, five hundred seventeen thousand, four hundred twenty-one".