87720865 has 4 divisors (see below), whose sum is σ = 105265044. Its totient is φ = 70176688.

The previous prime is 87720863. The next prime is 87720869. The reversal of 87720865 is 56802778.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 41589601 + 46131264 = 6449^2 + 6792^2 .

It is a cyclic number.

It is not a de Polignac number, because 87720865 - 2¹ = 87720863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87720863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8772082 + ... + 8772091.

It is an arithmetic number, because the mean of its divisors is an integer number (26316261).

Almost surely, 2^87720865 is an apocalyptic number.

It is an amenable number.

87720865 is a deficient number, since it is larger than the sum of its proper divisors (17544179).

87720865 is a wasteful number, since it uses less digits than its factorization.

87720865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17544178.

The product of its (nonzero) digits is 188160, while the sum is 43.

The square root of 87720865 is about 9365.9417572394. The cubic root of 87720865 is about 444.3252240063.

The spelling of 87720865 in words is "eighty-seven million, seven hundred twenty thousand, eight hundred sixty-five".