221020496821 has 2 divisors, whose sum is σ = 221020496822. Its totient is φ = 221020496820.

The previous prime is 221020496803. The next prime is 221020496869. The reversal of 221020496821 is 128694020122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 131431626225 + 89588870596 = 362535^2 + 299314^2 .

It is a cyclic number.

It is not a de Polignac number, because 221020496821 - 2⁹ = 221020496309 is a prime.

It is a super-2 number, since 2×221020496821² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221020496881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510248410 + 110510248411.

It is an arithmetic number, because the mean of its divisors is an integer number (110510248411).

Almost surely, 2^221020496821 is an apocalyptic number.

It is an amenable number.

221020496821 is a deficient number, since it is larger than the sum of its proper divisors (1).

221020496821 is an equidigital number, since it uses as much as digits as its factorization.

221020496821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27648, while the sum is 37.

The spelling of 221020496821 in words is "two hundred twenty-one billion, twenty million, four hundred ninety-six thousand, eight hundred twenty-one".