21085867 has 8 divisors (see below), whose sum is σ = 23538240. Its totient is φ = 18722760.

The previous prime is 21085853. The next prime is 21085879. The reversal of 21085867 is 76858012.

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 21085867 - 2⁷ = 21085739 is a prime.

It is a super-2 number, since 2×21085867² = 889227574283378, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21085837) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21817 + ... + 22762.

It is an arithmetic number, because the mean of its divisors is an integer number (2942280).

Almost surely, 2^21085867 is an apocalyptic number.

21085867 is a deficient number, since it is larger than the sum of its proper divisors (2452373).

21085867 is a wasteful number, since it uses less digits than its factorization.

21085867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44633.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 21085867 is about 4591.9349951845. The cubic root of 21085867 is about 276.2679388854.

It can be divided in two parts, 210858 and 67, that added together give a triangular number (210925 = T₆₄₉).

The spelling of 21085867 in words is "twenty-one million, eighty-five thousand, eight hundred sixty-seven".