87721609 has 4 divisors (see below), whose sum is σ = 91535616. Its totient is φ = 83907604.

The previous prime is 87721603. The next prime is 87721619. The reversal of 87721609 is 90612778.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 87721609 - 2⁵ = 87721577 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87721603) 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, 1906969 + ... + 1907014.

It is an arithmetic number, because the mean of its divisors is an integer number (22883904).

Almost surely, 2^87721609 is an apocalyptic number.

It is an amenable number.

87721609 is a deficient number, since it is larger than the sum of its proper divisors (3814007).

87721609 is a wasteful number, since it uses less digits than its factorization.

87721609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3814006.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 87721609 is about 9365.9814755315. The cubic root of 87721609 is about 444.3264801765.

The spelling of 87721609 in words is "eighty-seven million, seven hundred twenty-one thousand, six hundred nine".