221500155 has 16 divisors (see below), whose sum is σ = 354857760. Its totient is φ = 117980928.

The previous prime is 221500141. The next prime is 221500159. The reversal of 221500155 is 551005122.

It is not a de Polignac number, because 221500155 - 2⁹ = 221499643 is a prime.

It is a super-4 number, since 4×221500155⁴ (a number of 34 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (221500159) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3009 + ... + 21261.

It is an arithmetic number, because the mean of its divisors is an integer number (22178610).

Almost surely, 2^221500155 is an apocalyptic number.

221500155 is a deficient number, since it is larger than the sum of its proper divisors (133357605).

221500155 is a wasteful number, since it uses less digits than its factorization.

221500155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19070.

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 221500155 is about 14882.8812734631. The cubic root of 221500155 is about 605.0501108232.

Adding to 221500155 its reverse (551005122), we get a palindrome (772505277).

The spelling of 221500155 in words is "two hundred twenty-one million, five hundred thousand, one hundred fifty-five".