221321251 has 2 divisors, whose sum is σ = 221321252. Its totient is φ = 221321250.

The previous prime is 221321209. The next prime is 221321267. The reversal of 221321251 is 152123122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221321251 - 2²¹ = 219224099 is a prime.

It is a super-2 number, since 2×221321251² = 97966192288410002, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221321281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110660625 + 110660626.

It is an arithmetic number, because the mean of its divisors is an integer number (110660626).

Almost surely, 2^221321251 is an apocalyptic number.

221321251 is a deficient number, since it is larger than the sum of its proper divisors (1).

221321251 is an equidigital number, since it uses as much as digits as its factorization.

221321251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 19.

The square root of 221321251 is about 14876.8696640120. The cubic root of 221321251 is about 604.8871688135.

Adding to 221321251 its reverse (152123122), we get a palindrome (373444373).

The spelling of 221321251 in words is "two hundred twenty-one million, three hundred twenty-one thousand, two hundred fifty-one".