21087867 has 8 divisors (see below), whose sum is σ = 28198224. Its totient is φ = 14018048.

The previous prime is 21087863. The next prime is 21087889. The reversal of 21087867 is 76878012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21087867 - 2² = 21087863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21087863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8898 + ... + 11015.

It is an arithmetic number, because the mean of its divisors is an integer number (3524778).

Almost surely, 2^21087867 is an apocalyptic number.

21087867 is a deficient number, since it is larger than the sum of its proper divisors (7110357).

21087867 is a wasteful number, since it uses less digits than its factorization.

21087867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20269.

The product of its (nonzero) digits is 37632, while the sum is 39.

The square root of 21087867 is about 4592.1527631384. The cubic root of 21087867 is about 276.2766733047.

The spelling of 21087867 in words is "twenty-one million, eighty-seven thousand, eight hundred sixty-seven".