221512155 has 32 divisors (see below), whose sum is σ = 365649984. Its totient is φ = 114425856.

The previous prime is 221512153. The next prime is 221512157. The reversal of 221512155 is 551215122.

It is an interprime number because it is at equal distance from previous prime (221512153) and next prime (221512157).

It is not a de Polignac number, because 221512155 - 2¹ = 221512153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221512153) 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 31 ways as a sum of consecutive naturals, for example, 141859 + ... + 143411.

It is an arithmetic number, because the mean of its divisors is an integer number (11426562).

Almost surely, 2^221512155 is an apocalyptic number.

221512155 is a deficient number, since it is larger than the sum of its proper divisors (144137829).

221512155 is a wasteful number, since it uses less digits than its factorization.

221512155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1855.

The product of its digits is 1000, while the sum is 24.

The square root of 221512155 is about 14883.2844157464. The cubic root of 221512155 is about 605.0610370311.

Adding to 221512155 its reverse (551215122), we get a palindrome (772727277).

The spelling of 221512155 in words is "two hundred twenty-one million, five hundred twelve thousand, one hundred fifty-five".