87740221 has 2 divisors, whose sum is σ = 87740222. Its totient is φ = 87740220.

The previous prime is 87740207. The next prime is 87740249. The reversal of 87740221 is 12204778.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 82628100 + 5112121 = 9090^2 + 2261^2 .

It is a cyclic number.

It is not a de Polignac number, because 87740221 - 2⁹ = 87739709 is a prime.

It is a super-2 number, since 2×87740221² = 15396692762257682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87740201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43870110 + 43870111.

It is an arithmetic number, because the mean of its divisors is an integer number (43870111).

Almost surely, 2^87740221 is an apocalyptic number.

It is an amenable number.

87740221 is a deficient number, since it is larger than the sum of its proper divisors (1).

87740221 is an equidigital number, since it uses as much as digits as its factorization.

87740221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 87740221 is about 9366.9750186493. The cubic root of 87740221 is about 444.3579023835.

Adding to 87740221 its reverse (12204778), we get a palindrome (99944999).

The spelling of 87740221 in words is "eighty-seven million, seven hundred forty thousand, two hundred twenty-one".