84217621 has 2 divisors, whose sum is σ = 84217622. Its totient is φ = 84217620.

The previous prime is 84217591. The next prime is 84217663. The reversal of 84217621 is 12671248.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 47748100 + 36469521 = 6910^2 + 6039^2 .

It is a cyclic number.

It is not a de Polignac number, because 84217621 - 2⁵ = 84217589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84214621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42108810 + 42108811.

It is an arithmetic number, because the mean of its divisors is an integer number (42108811).

Almost surely, 2^84217621 is an apocalyptic number.

It is an amenable number.

84217621 is a deficient number, since it is larger than the sum of its proper divisors (1).

84217621 is an equidigital number, since it uses as much as digits as its factorization.

84217621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 31.

The square root of 84217621 is about 9177.0159093248. The cubic root of 84217621 is about 438.3297923479.

Adding to 84217621 its reverse (12671248), we get a palindrome (96888869).

The spelling of 84217621 in words is "eighty-four million, two hundred seventeen thousand, six hundred twenty-one".