1555381231 has 2 divisors, whose sum is σ = 1555381232. Its totient is φ = 1555381230.

The previous prime is 1555381229. The next prime is 1555381237. The reversal of 1555381231 is 1321835551.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1555381231 - 2¹ = 1555381229 is a prime.

It is a super-2 number, since 2×1555381231² = 4838421547494150722, which contains 22 as substring.

Together with 1555381229, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555381237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777690615 + 777690616.

It is an arithmetic number, because the mean of its divisors is an integer number (777690616).

Almost surely, 2^1555381231 is an apocalyptic number.

1555381231 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555381231 is an equidigital number, since it uses as much as digits as its factorization.

1555381231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18000, while the sum is 34.

The square root of 1555381231 is about 39438.3218583144. The cubic root of 1555381231 is about 1158.6322640500.

The spelling of 1555381231 in words is "one billion, five hundred fifty-five million, three hundred eighty-one thousand, two hundred thirty-one".