1155555551 has 4 divisors (see below), whose sum is σ = 1157668632. Its totient is φ = 1153442472.

The previous prime is 1155555529. The next prime is 1155555553. The reversal of 1155555551 is 1555555511.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1555555511 = 211 ⋅7372301.

It is a cyclic number.

It is not a de Polignac number, because 1155555551 - 2⁶ = 1155555487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1155555553) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1055720 + ... + 1056813.

It is an arithmetic number, because the mean of its divisors is an integer number (289417158).

Almost surely, 2^1155555551 is an apocalyptic number.

1155555551 is a deficient number, since it is larger than the sum of its proper divisors (2113081).

1155555551 is an equidigital number, since it uses as much as digits as its factorization.

1155555551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2113080.

The product of its digits is 78125, while the sum is 38.

The square root of 1155555551 is about 33993.4633569456. The cubic root of 1155555551 is about 1049.3739430420.

The spelling of 1155555551 in words is "one billion, one hundred fifty-five million, five hundred fifty-five thousand, five hundred fifty-one".