1155438721 has 2 divisors, whose sum is σ = 1155438722. Its totient is φ = 1155438720.

The previous prime is 1155438617. The next prime is 1155438749. The reversal of 1155438721 is 1278345511.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1069617025 + 85821696 = 32705^2 + 9264^2 .

It is a cyclic number.

It is not a de Polignac number, because 1155438721 - 2¹⁷ = 1155307649 is a prime.

It is a super-2 number, since 2×1155438721² = 2670077275972231682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1155438521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 577719360 + 577719361.

It is an arithmetic number, because the mean of its divisors is an integer number (577719361).

Almost surely, 2^1155438721 is an apocalyptic number.

It is an amenable number.

1155438721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1155438721 is an equidigital number, since it uses as much as digits as its factorization.

1155438721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 33600, while the sum is 37.

The square root of 1155438721 is about 33991.7448949006. The cubic root of 1155438721 is about 1049.3385769390.

The spelling of 1155438721 in words is "one billion, one hundred fifty-five million, four hundred thirty-eight thousand, seven hundred twenty-one".