25728561 has 12 divisors (see below), whose sum is σ = 37261380. Its totient is φ = 17107200.

The previous prime is 25728557. The next prime is 25728569. The reversal of 25728561 is 16582752.

It is a happy number.

25728561 is a `hidden beast` number, since 2 + 572 + 85 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 22268961 + 3459600 = 4719^2 + 1860^2 .

It is not a de Polignac number, because 25728561 - 2² = 25728557 is a prime.

It is a super-2 number, since 2×25728561² = 1323917702261442, 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 (25728569) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45 + ... + 7173.

It is an arithmetic number, because the mean of its divisors is an integer number (3105115).

Almost surely, 2^25728561 is an apocalyptic number.

It is an amenable number.

25728561 is a deficient number, since it is larger than the sum of its proper divisors (11532819).

25728561 is a wasteful number, since it uses less digits than its factorization.

25728561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7536 (or 7533 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 25728561 is about 5072.3328952268. The cubic root of 25728561 is about 295.2150533778.

The spelling of 25728561 in words is "twenty-five million, seven hundred twenty-eight thousand, five hundred sixty-one".