221220531 has 32 divisors (see below), whose sum is σ = 375513600. Its totient is φ = 126087840.

The previous prime is 221220529. The next prime is 221220547. The reversal of 221220531 is 135022122.

It is not a de Polignac number, because 221220531 - 2¹ = 221220529 is a prime.

It is a super-2 number, since 2×221220531² = 97877046671843922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (221220581) 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, 85860 + ... + 88398.

It is an arithmetic number, because the mean of its divisors is an integer number (11734800).

Almost surely, 2^221220531 is an apocalyptic number.

221220531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221220531 is a deficient number, since it is larger than the sum of its proper divisors (154293069).

221220531 is a wasteful number, since it uses less digits than its factorization.

221220531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3016 (or 3010 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 221220531 is about 14873.4841580579. The cubic root of 221220531 is about 604.7953965148.

Adding to 221220531 its reverse (135022122), we get a palindrome (356242653).

The spelling of 221220531 in words is "two hundred twenty-one million, two hundred twenty thousand, five hundred thirty-one".