1555136991 has 6 divisors (see below), whose sum is σ = 2246309000. Its totient is φ = 1036757988.

The previous prime is 1555136983. The next prime is 1555137007. The reversal of 1555136991 is 1996315551.

1555136991 is a `hidden beast` number, since 1 + 5 + 551 + 3 + 6 + 9 + 91 = 666.

It is not a de Polignac number, because 1555136991 - 2³ = 1555136983 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 (1555136941) 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 5 ways as a sum of consecutive naturals, for example, 86396491 + ... + 86396508.

Almost surely, 2^1555136991 is an apocalyptic number.

1555136991 is a deficient number, since it is larger than the sum of its proper divisors (691172009).

1555136991 is a wasteful number, since it uses less digits than its factorization.

1555136991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172793005 (or 172793002 counting only the distinct ones).

The product of its digits is 182250, while the sum is 45.

The square root of 1555136991 is about 39435.2252561083. The cubic root of 1555136991 is about 1158.5716145766.

The spelling of 1555136991 in words is "one billion, five hundred fifty-five million, one hundred thirty-six thousand, nine hundred ninety-one".