215421155 has 4 divisors (see below), whose sum is σ = 258505392. Its totient is φ = 172336920.

The previous prime is 215421137. The next prime is 215421179. The reversal of 215421155 is 551124512.

215421155 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 215421155 - 2¹⁰ = 215420131 is a prime.

It is a Duffinian 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, 21542111 + ... + 21542120.

It is an arithmetic number, because the mean of its divisors is an integer number (64626348).

Almost surely, 2^215421155 is an apocalyptic number.

215421155 is a deficient number, since it is larger than the sum of its proper divisors (43084237).

215421155 is an equidigital number, since it uses as much as digits as its factorization.

215421155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43084236.

The product of its digits is 2000, while the sum is 26.

The square root of 215421155 is about 14677.2325388678. The cubic root of 215421155 is about 599.4635529246.

Adding to 215421155 its reverse (551124512), we get a palindrome (766545667).

The spelling of 215421155 in words is "two hundred fifteen million, four hundred twenty-one thousand, one hundred fifty-five".