21158659 has 4 divisors (see below), whose sum is σ = 22403304. Its totient is φ = 19914016.

The previous prime is 21158633. The next prime is 21158671. The reversal of 21158659 is 95685112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21158659 - 2⁹ = 21158147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21158959) 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 3 ways as a sum of consecutive naturals, for example, 622297 + ... + 622330.

It is an arithmetic number, because the mean of its divisors is an integer number (5600826).

Almost surely, 2^21158659 is an apocalyptic number.

21158659 is a deficient number, since it is larger than the sum of its proper divisors (1244645).

21158659 is a wasteful number, since it uses less digits than its factorization.

21158659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1244644.

The product of its digits is 21600, while the sum is 37.

The square root of 21158659 is about 4599.8542368210. The cubic root of 21158659 is about 276.5854817358.

The spelling of 21158659 in words is "twenty-one million, one hundred fifty-eight thousand, six hundred fifty-nine".