21158860 has 24 divisors (see below), whose sum is σ = 44936640. Its totient is φ = 8367744.

The previous prime is 21158843. The next prime is 21158899. The reversal of 21158860 is 6885112.

It is an unprimeable number.

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, 4164 + ... + 7723.

It is an arithmetic number, because the mean of its divisors is an integer number (1872360).

Almost surely, 2^21158860 is an apocalyptic number.

21158860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21158860 is an abundant number, since it is smaller than the sum of its proper divisors (23777780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21158860 is a wasteful number, since it uses less digits than its factorization.

21158860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11985 (or 11983 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 21158860 is about 4599.8760852875. The cubic root of 21158860 is about 276.5863575554.

The spelling of 21158860 in words is "twenty-one million, one hundred fifty-eight thousand, eight hundred sixty".