221542251 has 16 divisors (see below), whose sum is σ = 337822464. Its totient is φ = 126507744.

The previous prime is 221542247. The next prime is 221542291. The reversal of 221542251 is 152245122.

It is not a de Polignac number, because 221542251 - 2² = 221542247 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221542241) 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 15 ways as a sum of consecutive naturals, for example, 38760 + ... + 44106.

It is an arithmetic number, because the mean of its divisors is an integer number (21113904).

Almost surely, 2^221542251 is an apocalyptic number.

221542251 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221542251 is a deficient number, since it is larger than the sum of its proper divisors (116280213).

221542251 is a wasteful number, since it uses less digits than its factorization.

221542251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7330.

The product of its digits is 1600, while the sum is 24.

The square root of 221542251 is about 14884.2954485592. The cubic root of 221542251 is about 605.0884382247.

Adding to 221542251 its reverse (152245122), we get a palindrome (373787373).

The spelling of 221542251 in words is "two hundred twenty-one million, five hundred forty-two thousand, two hundred fifty-one".