155456221 has 2 divisors, whose sum is σ = 155456222. Its totient is φ = 155456220.

The previous prime is 155456179. The next prime is 155456299. The reversal of 155456221 is 122654551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 97239321 + 58216900 = 9861^2 + 7630^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155456221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155456321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77728110 + 77728111.

It is an arithmetic number, because the mean of its divisors is an integer number (77728111).

Almost surely, 2^155456221 is an apocalyptic number.

It is an amenable number.

155456221 is a deficient number, since it is larger than the sum of its proper divisors (1).

155456221 is an equidigital number, since it uses as much as digits as its factorization.

155456221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12000, while the sum is 31.

The square root of 155456221 is about 12468.2084117968. The cubic root of 155456221 is about 537.6950462860.

It can be divided in two parts, 1554 and 56221, that added together give a palindrome (57775).

The spelling of 155456221 in words is "one hundred fifty-five million, four hundred fifty-six thousand, two hundred twenty-one".