221505989 has 2 divisors, whose sum is σ = 221505990. Its totient is φ = 221505988.

The previous prime is 221505983. The next prime is 221506049. The reversal of 221505989 is 989505122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 220284964 + 1221025 = 14842^2 + 1105^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221505989 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221505983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110752994 + 110752995.

It is an arithmetic number, because the mean of its divisors is an integer number (110752995).

Almost surely, 2^221505989 is an apocalyptic number.

It is an amenable number.

221505989 is a deficient number, since it is larger than the sum of its proper divisors (1).

221505989 is an equidigital number, since it uses as much as digits as its factorization.

221505989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 221505989 is about 14883.0772691672. The cubic root of 221505989 is about 605.0554228306.

The spelling of 221505989 in words is "two hundred twenty-one million, five hundred five thousand, nine hundred eighty-nine".