1225681 has 4 divisors (see below), whose sum is σ = 1228212. Its totient is φ = 1223152.

The previous prime is 1225663. The next prime is 1225687. The reversal of 1225681 is 1865221.

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 518400 + 707281 = 720^2 + 841^2 .

It is a cyclic number.

It is not a de Polignac number, because 1225681 - 2¹¹ = 1223633 is a prime.

It is a super-2 number, since 2×1225681² = 3004587827522, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1225687) 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, 286 + ... + 1591.

It is an arithmetic number, because the mean of its divisors is an integer number (307053).

2^1225681 is an apocalyptic number.

It is an amenable number.

1225681 is a deficient number, since it is larger than the sum of its proper divisors (2531).

1225681 is an equidigital number, since it uses as much as digits as its factorization.

1225681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2530.

The product of its digits is 960, while the sum is 25.

The square root of 1225681 is about 1107.1047827555. The cubic root of 1225681 is about 107.0185719066.

The spelling of 1225681 in words is "one million, two hundred twenty-five thousand, six hundred eighty-one".