21158863 has 8 divisors (see below), whose sum is σ = 24440400. Its totient is φ = 18103680.

The previous prime is 21158843. The next prime is 21158899. The reversal of 21158863 is 36885112.

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 21158863 - 2¹³ = 21150671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158803) 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, 56388 + ... + 56761.

It is an arithmetic number, because the mean of its divisors is an integer number (3055050).

Almost surely, 2^21158863 is an apocalyptic number.

21158863 is a deficient number, since it is larger than the sum of its proper divisors (3281537).

21158863 is a wasteful number, since it uses less digits than its factorization.

21158863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113177.

The product of its digits is 11520, while the sum is 34.

The square root of 21158863 is about 4599.8764113832. The cubic root of 21158863 is about 276.5863706273.

The spelling of 21158863 in words is "twenty-one million, one hundred fifty-eight thousand, eight hundred sixty-three".