1555000001 has 4 divisors (see below), whose sum is σ = 1557381972. Its totient is φ = 1552618032.

The previous prime is 1554999991. The next prime is 1555000003. The reversal of 1555000001 is 1000005551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1000005551 = 569 ⋅1757479.

It can be written as a sum of positive squares in 2 ways, for example, as 333427600 + 1221572401 = 18260^2 + 34951^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1555000001 is a prime.

It is a super-2 number, since 2×1555000001² = 4836050006220000002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1555000003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1190006 + ... + 1191311.

It is an arithmetic number, because the mean of its divisors is an integer number (389345493).

Almost surely, 2^1555000001 is an apocalyptic number.

It is an amenable number.

1555000001 is a deficient number, since it is larger than the sum of its proper divisors (2381971).

1555000001 is an equidigital number, since it uses as much as digits as its factorization.

1555000001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2381970.

The product of its (nonzero) digits is 125, while the sum is 17.

The square root of 1555000001 is about 39433.4883189403. The cubic root of 1555000001 is about 1158.5375945542.

Adding to 1555000001 its reverse (1000005551), we get a palindrome (2555005552).

The spelling of 1555000001 in words is "one billion, five hundred fifty-five million, one", and thus it is an aban number.