25781217 has 32 divisors (see below), whose sum is σ = 43130880. Its totient is φ = 13307520.

The previous prime is 25781213. The next prime is 25781219. The reversal of 25781217 is 71218752.

It is not a de Polignac number, because 25781217 - 2² = 25781213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (25781213) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 53584 + ... + 54062.

It is an arithmetic number, because the mean of its divisors is an integer number (1347840).

Almost surely, 2^25781217 is an apocalyptic number.

It is an amenable number.

25781217 is a deficient number, since it is larger than the sum of its proper divisors (17349663).

25781217 is a wasteful number, since it uses less digits than its factorization.

25781217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733.

The product of its digits is 7840, while the sum is 33.

The square root of 25781217 is about 5077.5207532811. The cubic root of 25781217 is about 295.4163115725.

Adding to 25781217 its reverse (71218752), we get a palindrome (96999969).

The spelling of 25781217 in words is "twenty-five million, seven hundred eighty-one thousand, two hundred seventeen".