221220251 has 32 divisors (see below), whose sum is σ = 269913600. Its totient is φ = 181071072.

The previous prime is 221220229. The next prime is 221220257. The reversal of 221220251 is 152022122.

It is not a de Polignac number, because 221220251 - 2¹⁴ = 221203867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221220257) 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 31 ways as a sum of consecutive naturals, for example, 781556 + ... + 781838.

It is an arithmetic number, because the mean of its divisors is an integer number (8434800).

Almost surely, 2^221220251 is an apocalyptic number.

221220251 is a deficient number, since it is larger than the sum of its proper divisors (48693349).

221220251 is an equidigital number, since it uses as much as digits as its factorization.

221220251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400 (or 386 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 221220251 is about 14873.4747453310. The cubic root of 221220251 is about 604.7951413504.

Adding to 221220251 its reverse (152022122), we get a palindrome (373242373).

The spelling of 221220251 in words is "two hundred twenty-one million, two hundred twenty thousand, two hundred fifty-one".