221394557 has 2 divisors, whose sum is σ = 221394558. Its totient is φ = 221394556.

The previous prime is 221394541. The next prime is 221394601. The reversal of 221394557 is 755493122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210279001 + 11115556 = 14501^2 + 3334^2 .

It is a cyclic number.

It is not a de Polignac number, because 221394557 - 2⁴ = 221394541 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221394557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221394457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110697278 + 110697279.

It is an arithmetic number, because the mean of its divisors is an integer number (110697279).

Almost surely, 2^221394557 is an apocalyptic number.

It is an amenable number.

221394557 is a deficient number, since it is larger than the sum of its proper divisors (1).

221394557 is an equidigital number, since it uses as much as digits as its factorization.

221394557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 38.

The square root of 221394557 is about 14879.3332175874. Note that the first 3 decimals coincide. The cubic root of 221394557 is about 604.9539449950.

The spelling of 221394557 in words is "two hundred twenty-one million, three hundred ninety-four thousand, five hundred fifty-seven".