1551565243 has 4 divisors (see below), whose sum is σ = 1557290848. Its totient is φ = 1545839640.

The previous prime is 1551565241. The next prime is 1551565261. The reversal of 1551565243 is 3425651551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3425651551 = 7 ⋅489378793.

It is a cyclic number.

It is not a de Polignac number, because 1551565243 - 2¹ = 1551565241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551565241) 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, 2862396 + ... + 2862937.

It is an arithmetic number, because the mean of its divisors is an integer number (389322712).

Almost surely, 2^1551565243 is an apocalyptic number.

1551565243 is a deficient number, since it is larger than the sum of its proper divisors (5725605).

1551565243 is an equidigital number, since it uses as much as digits as its factorization.

1551565243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5725604.

The product of its digits is 90000, while the sum is 37.

The square root of 1551565243 is about 39389.9129600460. The cubic root of 1551565243 is about 1157.6839547352.

The spelling of 1551565243 in words is "one billion, five hundred fifty-one million, five hundred sixty-five thousand, two hundred forty-three".