25516021 has 4 divisors (see below), whose sum is σ = 25529292. Its totient is φ = 25502752.

The previous prime is 25516013. The next prime is 25516037. The reversal of 25516021 is 12061552.

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 17892900 + 7623121 = 4230^2 + 2761^2 .

It is a cyclic number.

It is not a de Polignac number, because 25516021 - 2³ = 25516013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 25515983 and 25516001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25516061) 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, 3136 + ... + 7801.

It is an arithmetic number, because the mean of its divisors is an integer number (6382323).

Almost surely, 2^25516021 is an apocalyptic number.

It is an amenable number.

25516021 is a deficient number, since it is larger than the sum of its proper divisors (13271).

25516021 is a wasteful number, since it uses less digits than its factorization.

25516021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13270.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 25516021 is about 5051.3385354775. The cubic root of 25516021 is about 294.3998946826.

Adding to 25516021 its reverse (12061552), we get a palindrome (37577573).

The spelling of 25516021 in words is "twenty-five million, five hundred sixteen thousand, twenty-one".