221421651509 has 2 divisors, whose sum is σ = 221421651510. Its totient is φ = 221421651508.

The previous prime is 221421651491. The next prime is 221421651569. The reversal of 221421651509 is 905156124122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210180987025 + 11240664484 = 458455^2 + 106022^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221421651509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221421651569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110710825754 + 110710825755.

It is an arithmetic number, because the mean of its divisors is an integer number (110710825755).

Almost surely, 2^221421651509 is an apocalyptic number.

It is an amenable number.

221421651509 is a deficient number, since it is larger than the sum of its proper divisors (1).

221421651509 is an equidigital number, since it uses as much as digits as its factorization.

221421651509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 38.

The spelling of 221421651509 in words is "two hundred twenty-one billion, four hundred twenty-one million, six hundred fifty-one thousand, five hundred nine".