42206561 has 2 divisors, whose sum is σ = 42206562. Its totient is φ = 42206560.

The previous prime is 42206551. The next prime is 42206569. The reversal of 42206561 is 16560224.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39450961 + 2755600 = 6281^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 42206561 - 2¹⁴ = 42190177 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 42206561.

It is not a weakly prime, because it can be changed into another prime (42206569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21103280 + 21103281.

It is an arithmetic number, because the mean of its divisors is an integer number (21103281).

Almost surely, 2^42206561 is an apocalyptic number.

It is an amenable number.

42206561 is a deficient number, since it is larger than the sum of its proper divisors (1).

42206561 is an equidigital number, since it uses as much as digits as its factorization.

42206561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 42206561 is about 6496.6576791455. The cubic root of 42206561 is about 348.1715832638.

Adding to 42206561 its reverse (16560224), we get a palindrome (58766785).

The spelling of 42206561 in words is "forty-two million, two hundred six thousand, five hundred sixty-one".