1555640431 has 4 divisors (see below), whose sum is σ = 1555854264. Its totient is φ = 1555426600.

The previous prime is 1555640407. The next prime is 1555640453. The reversal of 1555640431 is 1340465551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1340465551 = 113 ⋅11862527.

It is a cyclic number.

It is not a de Polignac number, because 1555640431 - 2²⁷ = 1421422703 is a prime.

It is a super-2 number, since 2×1555640431² = 4840034301123731522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1555640831) 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, 95605 + ... + 110686.

It is an arithmetic number, because the mean of its divisors is an integer number (388963566).

Almost surely, 2^1555640431 is an apocalyptic number.

1555640431 is a deficient number, since it is larger than the sum of its proper divisors (213833).

1555640431 is an equidigital number, since it uses as much as digits as its factorization.

1555640431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213832.

The product of its (nonzero) digits is 36000, while the sum is 34.

The square root of 1555640431 is about 39441.6078652988. The cubic root of 1555640431 is about 1158.6966214341.

The spelling of 1555640431 in words is "one billion, five hundred fifty-five million, six hundred forty thousand, four hundred thirty-one".