215531551 has 16 divisors (see below), whose sum is σ = 229892544. Its totient is φ = 201636864.

The previous prime is 215531539. The next prime is 215531557. The reversal of 215531551 is 155135512.

It is a cyclic number.

It is not a de Polignac number, because 215531551 - 2¹⁹ = 215007263 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215531557) 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 15 ways as a sum of consecutive naturals, for example, 229555 + ... + 230491.

It is an arithmetic number, because the mean of its divisors is an integer number (14368284).

Almost surely, 2^215531551 is an apocalyptic number.

215531551 is a deficient number, since it is larger than the sum of its proper divisors (14360993).

215531551 is a wasteful number, since it uses less digits than its factorization.

215531551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1170.

The product of its digits is 3750, while the sum is 28.

The square root of 215531551 is about 14680.9928478969. The cubic root of 215531551 is about 599.5659369838.

It can be divided in two parts, 21553 and 1551, that added together give a square (23104 = 152²).

The spelling of 215531551 in words is "two hundred fifteen million, five hundred thirty-one thousand, five hundred fifty-one".