221500001 has 4 divisors (see below), whose sum is σ = 223460292. Its totient is φ = 219539712.

The previous prime is 221499989. The next prime is 221500039. The reversal of 221500001 is 100005122.

221500001 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 can be written as a sum of positive squares in 2 ways, for example, as 19149376 + 202350625 = 4376^2 + 14225^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221500001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221500501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 979976 + ... + 980201.

It is an arithmetic number, because the mean of its divisors is an integer number (55865073).

Almost surely, 2^221500001 is an apocalyptic number.

It is an amenable number.

221500001 is a deficient number, since it is larger than the sum of its proper divisors (1960291).

221500001 is a wasteful number, since it uses less digits than its factorization.

221500001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1960290.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 221500001 is about 14882.8760997329. The cubic root of 221500001 is about 605.0499706010.

Adding to 221500001 its reverse (100005122), we get a palindrome (321505123).

The spelling of 221500001 in words is "two hundred twenty-one million, five hundred thousand, one".