1001231555 has 4 divisors (see below), whose sum is σ = 1201477872. Its totient is φ = 800985240.

The previous prime is 1001231549. The next prime is 1001231587. The reversal of 1001231555 is 5551321001.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1001231555 - 2¹² = 1001227459 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1001231555.

It is an unprimeable number.

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, 100123151 + ... + 100123160.

It is an arithmetic number, because the mean of its divisors is an integer number (300369468).

Almost surely, 2^1001231555 is an apocalyptic number.

1001231555 is a deficient number, since it is larger than the sum of its proper divisors (200246317).

1001231555 is an equidigital number, since it uses as much as digits as its factorization.

1001231555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200246316.

The product of its (nonzero) digits is 750, while the sum is 23.

The square root of 1001231555 is about 31642.2432042989. The cubic root of 1001231555 is about 1000.4103499232.

Adding to 1001231555 its reverse (5551321001), we get a palindrome (6552552556).

The spelling of 1001231555 in words is "one billion, one million, two hundred thirty-one thousand, five hundred fifty-five".