221311001 has 4 divisors (see below), whose sum is σ = 221482932. Its totient is φ = 221139072.

The previous prime is 221310911. The next prime is 221311003. The reversal of 221311001 is 100113122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 100113122 = 2 ⋅50056561.

It can be written as a sum of positive squares in 2 ways, for example, as 220819600 + 491401 = 14860^2 + 701^2 .

It is a cyclic number.

It is not a de Polignac number, because 221311001 - 2¹⁸ = 221048857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221311003) 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, 84020 + ... + 86613.

It is an arithmetic number, because the mean of its divisors is an integer number (55370733).

Almost surely, 2^221311001 is an apocalyptic number.

It is an amenable number.

221311001 is a deficient number, since it is larger than the sum of its proper divisors (171931).

221311001 is a wasteful number, since it uses less digits than its factorization.

221311001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171930.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 221311001 is about 14876.5251655082. The cubic root of 221311001 is about 604.8778306694.

Adding to 221311001 its reverse (100113122), we get a palindrome (321424123).

It can be divided in two parts, 22131 and 1001, that added together give a palindrome (23132).

The spelling of 221311001 in words is "two hundred twenty-one million, three hundred eleven thousand, one".