8721691 has 4 divisors (see below), whose sum is σ = 9514584. Its totient is φ = 7928800.

The previous prime is 8721673. The next prime is 8721701. The reversal of 8721691 is 1961278.

It is a happy number.

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

It is not a de Polignac number, because 8721691 - 2¹⁹ = 8197403 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (8721631) 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, 396430 + ... + 396451.

It is an arithmetic number, because the mean of its divisors is an integer number (2378646).

Almost surely, 2^8721691 is an apocalyptic number.

8721691 is a deficient number, since it is larger than the sum of its proper divisors (792893).

8721691 is a wasteful number, since it uses less digits than its factorization.

8721691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792892.

The product of its digits is 6048, while the sum is 34.

The square root of 8721691 is about 2953.2509205958. The cubic root of 8721691 is about 205.8417973466.

The spelling of 8721691 in words is "eight million, seven hundred twenty-one thousand, six hundred ninety-one".