221640121 has 16 divisors (see below), whose sum is σ = 235799424. Its totient is φ = 207902464.

The previous prime is 221640113. The next prime is 221640131. The reversal of 221640121 is 121046122.

It is a cyclic number.

It is not a de Polignac number, because 221640121 - 2³ = 221640113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221640131) 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, 277695 + ... + 278491.

It is an arithmetic number, because the mean of its divisors is an integer number (14737464).

Almost surely, 2^221640121 is an apocalyptic number.

It is an amenable number.

221640121 is a deficient number, since it is larger than the sum of its proper divisors (14159303).

221640121 is a wasteful number, since it uses less digits than its factorization.

221640121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 221640121 is about 14887.5827789470. The cubic root of 221640121 is about 605.1775277578.

Adding to 221640121 its reverse (121046122), we get a palindrome (342686243).

The spelling of 221640121 in words is "two hundred twenty-one million, six hundred forty thousand, one hundred twenty-one".