221561689 has 2 divisors, whose sum is σ = 221561690. Its totient is φ = 221561688.

The previous prime is 221561651. The next prime is 221561693. The reversal of 221561689 is 986165122.

221561689 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., 180499225 + 41062464 = 13435^2 + 6408^2 .

It is a cyclic number.

It is not a de Polignac number, because 221561689 - 2²⁵ = 188007257 is a prime.

It is not a weakly prime, because it can be changed into another prime (221565689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110780844 + 110780845.

It is an arithmetic number, because the mean of its divisors is an integer number (110780845).

Almost surely, 2^221561689 is an apocalyptic number.

It is an amenable number.

221561689 is a deficient number, since it is larger than the sum of its proper divisors (1).

221561689 is an equidigital number, since it uses as much as digits as its factorization.

221561689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 40.

The square root of 221561689 is about 14884.9484043446. The cubic root of 221561689 is about 605.1061344204.

The spelling of 221561689 in words is "two hundred twenty-one million, five hundred sixty-one thousand, six hundred eighty-nine".