221220506 has 16 divisors (see below), whose sum is σ = 357674184. Its totient is φ = 102010944.

The previous prime is 221220499. The next prime is 221220523. The reversal of 221220506 is 605022122.

It can be written as a sum of positive squares in 4 ways, for example, as 201498025 + 19722481 = 14195^2 + 4441^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32600 + ... + 38796.

Almost surely, 2^221220506 is an apocalyptic number.

221220506 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

221220506 is a deficient number, since it is larger than the sum of its proper divisors (136453678).

221220506 is a wasteful number, since it uses less digits than its factorization.

221220506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7585.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 221220506 is about 14873.4833176361. The cubic root of 221220506 is about 604.7953737323.

Adding to 221220506 its reverse (605022122), we get a palindrome (826242628).

The spelling of 221220506 in words is "two hundred twenty-one million, two hundred twenty thousand, five hundred six".