8691021 has 12 divisors (see below), whose sum is σ = 12639900. Its totient is φ = 5754240.

The previous prime is 8691019. The next prime is 8691043. The reversal of 8691021 is 1201968.

It can be written as a sum of positive squares in 2 ways, for example, as 4888521 + 3802500 = 2211^2 + 1950^2 .

It is not a de Polignac number, because 8691021 - 2¹ = 8691019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8691091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1900 + ... + 4581.

It is an arithmetic number, because the mean of its divisors is an integer number (1053325).

Almost surely, 2^8691021 is an apocalyptic number.

It is an amenable number.

8691021 is a deficient number, since it is larger than the sum of its proper divisors (3948879).

8691021 is a wasteful number, since it uses less digits than its factorization.

8691021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6636 (or 6633 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 8691021 is about 2948.0537647743. The cubic root of 8691021 is about 205.6002317090.

Adding to 8691021 its reverse (1201968), we get a palindrome (9892989).

The spelling of 8691021 in words is "eight million, six hundred ninety-one thousand, twenty-one".