215551 has 12 divisors (see below), whose sum is σ = 258552. Its totient is φ = 179088.

The previous prime is 215531. The next prime is 215563. The reversal of 215551 is 155512.

It is a de Polignac number, because none of the positive numbers 2^k-215551 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215521) 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 11 ways as a sum of consecutive naturals, for example, 2556 + ... + 2638.

It is an arithmetic number, because the mean of its divisors is an integer number (21546).

2²¹⁵⁵⁵¹ is an apocalyptic number.

215551 is a deficient number, since it is larger than the sum of its proper divisors (43001).

215551 is an equidigital number, since it uses as much as digits as its factorization.

215551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150 (or 143 counting only the distinct ones).

The product of its digits is 250, while the sum is 19.

The square root of 215551 is about 464.2747031661. The cubic root of 215551 is about 59.9583970859.

The spelling of 215551 in words is "two hundred fifteen thousand, five hundred fifty-one".