21384861 has 32 divisors (see below), whose sum is σ = 32918400. Its totient is φ = 12257280.

The previous prime is 21384841. The next prime is 21384877. The reversal of 21384861 is 16848312.

It is not a de Polignac number, because 21384861 - 2⁵ = 21384829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21384841) 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 31 ways as a sum of consecutive naturals, for example, 27721 + ... + 28481.

It is an arithmetic number, because the mean of its divisors is an integer number (1028700).

Almost surely, 2^21384861 is an apocalyptic number.

It is an amenable number.

21384861 is a deficient number, since it is larger than the sum of its proper divisors (11533539).

21384861 is a wasteful number, since it uses less digits than its factorization.

21384861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 829.

The product of its digits is 9216, while the sum is 33.

The square root of 21384861 is about 4624.3768228811. The cubic root of 21384861 is about 277.5676257553.

The spelling of 21384861 in words is "twenty-one million, three hundred eighty-four thousand, eight hundred sixty-one".