221020531 has 2 divisors, whose sum is σ = 221020532. Its totient is φ = 221020530.

The previous prime is 221020523. The next prime is 221020537. The reversal of 221020531 is 135020122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221020531 - 2³ = 221020523 is a prime.

It is a super-2 number, since 2×221020531² = 97700150247043922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221020537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510265 + 110510266.

It is an arithmetic number, because the mean of its divisors is an integer number (110510266).

Almost surely, 2^221020531 is an apocalyptic number.

221020531 is a deficient number, since it is larger than the sum of its proper divisors (1).

221020531 is an equidigital number, since it uses as much as digits as its factorization.

221020531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 221020531 is about 14866.7592635382. The cubic root of 221020531 is about 604.6130813847.

Adding to 221020531 its reverse (135020122), we get a palindrome (356040653).

The spelling of 221020531 in words is "two hundred twenty-one million, twenty thousand, five hundred thirty-one".