25221781 has 4 divisors (see below), whose sum is σ = 27161932. Its totient is φ = 23281632.

The previous prime is 25221773. The next prime is 25221787. The reversal of 25221781 is 18712252.

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 15673681 + 9548100 = 3959^2 + 3090^2 .

It is a cyclic number.

It is not a de Polignac number, because 25221781 - 2³ = 25221773 is a prime.

It is a super-2 number, since 2×25221781² = 1272276473623922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25221787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 970056 + ... + 970081.

It is an arithmetic number, because the mean of its divisors is an integer number (6790483).

Almost surely, 2^25221781 is an apocalyptic number.

It is an amenable number.

25221781 is a deficient number, since it is larger than the sum of its proper divisors (1940151).

25221781 is a wasteful number, since it uses less digits than its factorization.

25221781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1940150.

The product of its digits is 2240, while the sum is 28.

The square root of 25221781 is about 5022.1291301598. The cubic root of 25221781 is about 293.2638849306.

The spelling of 25221781 in words is "twenty-five million, two hundred twenty-one thousand, seven hundred eighty-one".