221540251 has 4 divisors (see below), whose sum is σ = 229179600. Its totient is φ = 213900904.

The previous prime is 221540219. The next prime is 221540269. The reversal of 221540251 is 152045122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 152045122 = 2 ⋅76022561.

It is a cyclic number.

It is not a de Polignac number, because 221540251 - 2⁵ = 221540219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221540951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3819631 + ... + 3819688.

It is an arithmetic number, because the mean of its divisors is an integer number (57294900).

Almost surely, 2^221540251 is an apocalyptic number.

221540251 is a deficient number, since it is larger than the sum of its proper divisors (7639349).

221540251 is an equidigital number, since it uses as much as digits as its factorization.

221540251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7639348.

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 221540251 is about 14884.2282635009. The cubic root of 221540251 is about 605.0866173824.

Adding to 221540251 its reverse (152045122), we get a palindrome (373585373).

The spelling of 221540251 in words is "two hundred twenty-one million, five hundred forty thousand, two hundred fifty-one".