225155921 has 2 divisors, whose sum is σ = 225155922. Its totient is φ = 225155920.

The previous prime is 225155911. The next prime is 225155929. The reversal of 225155921 is 129551522.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 195300625 + 29855296 = 13975^2 + 5464^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-225155921 is a prime.

It is a super-2 number, since 2×225155921² = 101390377522716482, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_12390953 and since 225155921 and 12390953 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (225155929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 112577960 + 112577961.

It is an arithmetic number, because the mean of its divisors is an integer number (112577961).

Almost surely, 2^225155921 is an apocalyptic number.

It is an amenable number.

225155921 is a deficient number, since it is larger than the sum of its proper divisors (1).

225155921 is an equidigital number, since it uses as much as digits as its factorization.

225155921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 32.

The square root of 225155921 is about 15005.1964665578. The cubic root of 225155921 is about 608.3606623781.

The spelling of 225155921 in words is "two hundred twenty-five million, one hundred fifty-five thousand, nine hundred twenty-one".