221554961 has 2 divisors, whose sum is σ = 221554962. Its totient is φ = 221554960.

The previous prime is 221554943. The next prime is 221554969. The reversal of 221554961 is 169455122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 172764736 + 48790225 = 13144^2 + 6985^2 .

It is a cyclic number.

It is not a de Polignac number, because 221554961 - 2¹⁸ = 221292817 is a prime.

It is not a weakly prime, because it can be changed into another prime (221554969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110777480 + 110777481.

It is an arithmetic number, because the mean of its divisors is an integer number (110777481).

Almost surely, 2^221554961 is an apocalyptic number.

It is an amenable number.

221554961 is a deficient number, since it is larger than the sum of its proper divisors (1).

221554961 is an equidigital number, since it uses as much as digits as its factorization.

221554961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 35.

The square root of 221554961 is about 14884.7224025173. The cubic root of 221554961 is about 605.1000094216.

The spelling of 221554961 in words is "two hundred twenty-one million, five hundred fifty-four thousand, nine hundred sixty-one".