221421251705509 has 2 divisors, whose sum is σ = 221421251705510. Its totient is φ = 221421251705508.

The previous prime is 221421251705371. The next prime is 221421251705527. The reversal of 221421251705509 is 905507152124122.

221421251705509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125324599353409 + 96096652352100 = 11194847^2 + 9802890^2 .

It is a cyclic number.

It is not a de Polignac number, because 221421251705509 - 2²¹ = 221421249608357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221421251708509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110710625852754 + 110710625852755.

It is an arithmetic number, because the mean of its divisors is an integer number (110710625852755).

Almost surely, 2^{221421251705509} is an apocalyptic number.

It is an amenable number.

221421251705509 is a deficient number, since it is larger than the sum of its proper divisors (1).

221421251705509 is an equidigital number, since it uses as much as digits as its factorization.

221421251705509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504000, while the sum is 46.

The spelling of 221421251705509 in words is "two hundred twenty-one trillion, four hundred twenty-one billion, two hundred fifty-one million, seven hundred five thousand, five hundred nine".