51531565 has 8 divisors (see below), whose sum is σ = 63509400. Its totient is φ = 40110912.

The previous prime is 51531563. The next prime is 51531577. The reversal of 51531565 is 56513515.

51531565 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 12830724 + 38700841 = 3582^2 + 6221^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51531565 - 2¹ = 51531563 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51531563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 139090 + ... + 139459.

It is an arithmetic number, because the mean of its divisors is an integer number (7938675).

Almost surely, 2^51531565 is an apocalyptic number.

It is an amenable number.

51531565 is a deficient number, since it is larger than the sum of its proper divisors (11977835).

51531565 is a wasteful number, since it uses less digits than its factorization.

51531565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278591.

The product of its digits is 11250, while the sum is 31.

The square root of 51531565 is about 7178.5489480814. The cubic root of 51531565 is about 372.1269390856.

The spelling of 51531565 in words is "fifty-one million, five hundred thirty-one thousand, five hundred sixty-five".