221287973 has 2 divisors, whose sum is σ = 221287974. Its totient is φ = 221287972.

The previous prime is 221287961. The next prime is 221288021. The reversal of 221287973 is 379782122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 174187204 + 47100769 = 13198^2 + 6863^2 .

It is a cyclic number.

It is not a de Polignac number, because 221287973 - 2¹⁶ = 221222437 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221287973.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221247973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110643986 + 110643987.

It is an arithmetic number, because the mean of its divisors is an integer number (110643987).

Almost surely, 2^221287973 is an apocalyptic number.

It is an amenable number.

221287973 is a deficient number, since it is larger than the sum of its proper divisors (1).

221287973 is an equidigital number, since it uses as much as digits as its factorization.

221287973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 41.

The square root of 221287973 is about 14875.7511743105. The cubic root of 221287973 is about 604.8568502244.

The spelling of 221287973 in words is "two hundred twenty-one million, two hundred eighty-seven thousand, nine hundred seventy-three".