215866855 has 4 divisors (see below), whose sum is σ = 259040232. Its totient is φ = 172693480.

The previous prime is 215866823. The next prime is 215866883. The reversal of 215866855 is 558668512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 215866855 - 2⁵ = 215866823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21586681 + ... + 21586690.

It is an arithmetic number, because the mean of its divisors is an integer number (64760058).

Almost surely, 2^215866855 is an apocalyptic number.

215866855 is a deficient number, since it is larger than the sum of its proper divisors (43173377).

215866855 is an equidigital number, since it uses as much as digits as its factorization.

215866855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43173376.

The product of its digits is 576000, while the sum is 46.

The square root of 215866855 is about 14692.4080735596. The cubic root of 215866855 is about 599.8766922530.

It can be divided in two parts, 21586 and 6855, that added together give a triangular number (28441 = T₂₃₈).

The spelling of 215866855 in words is "two hundred fifteen million, eight hundred sixty-six thousand, eight hundred fifty-five".