87207721 has 2 divisors, whose sum is σ = 87207722. Its totient is φ = 87207720.

The previous prime is 87207719. The next prime is 87207767. The reversal of 87207721 is 12770278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83521321 + 3686400 = 9139^2 + 1920^2 .

It is a cyclic number.

It is not a de Polignac number, because 87207721 - 2¹ = 87207719 is a prime.

Together with 87207719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (87207221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43603860 + 43603861.

It is an arithmetic number, because the mean of its divisors is an integer number (43603861).

Almost surely, 2^87207721 is an apocalyptic number.

It is an amenable number.

87207721 is a deficient number, since it is larger than the sum of its proper divisors (1).

87207721 is an equidigital number, since it uses as much as digits as its factorization.

87207721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10976, while the sum is 34.

The square root of 87207721 is about 9338.5074289203. The cubic root of 87207721 is about 443.4571338479.

Adding to 87207721 its reverse (12770278), we get a palindrome (99977999).

The spelling of 87207721 in words is "eighty-seven million, two hundred seven thousand, seven hundred twenty-one".