87209621 has 2 divisors, whose sum is σ = 87209622. Its totient is φ = 87209620.

The previous prime is 87209599. The next prime is 87209623. The reversal of 87209621 is 12690278.

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., 66178225 + 21031396 = 8135^2 + 4586^2 .

It is a cyclic number.

It is not a de Polignac number, because 87209621 - 2⁶ = 87209557 is a prime.

It is a Sophie Germain prime.

Together with 87209623, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87209623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43604810 + 43604811.

It is an arithmetic number, because the mean of its divisors is an integer number (43604811).

Almost surely, 2^87209621 is an apocalyptic number.

It is an amenable number.

87209621 is a deficient number, since it is larger than the sum of its proper divisors (1).

87209621 is an equidigital number, since it uses as much as digits as its factorization.

87209621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 87209621 is about 9338.6091576851. The cubic root of 87209621 is about 443.4603543671.

Adding to 87209621 its reverse (12690278), we get a palindrome (99899899).

The spelling of 87209621 in words is "eighty-seven million, two hundred nine thousand, six hundred twenty-one".