21520858 has 8 divisors (see below), whose sum is σ = 32303700. Its totient is φ = 10752960.

The previous prime is 21520853. The next prime is 21520867. The reversal of 21520858 is 85802512.

It can be written as a sum of positive squares in 2 ways, for example, as 21464689 + 56169 = 4633^2 + 237^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21520853) 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, 1138 + ... + 6658.

Almost surely, 2^21520858 is an apocalyptic number.

21520858 is a deficient number, since it is larger than the sum of its proper divisors (10782842).

21520858 is a wasteful number, since it uses less digits than its factorization.

21520858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7472.

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 21520858 is about 4639.0578784921. The cubic root of 21520858 is about 278.1547798437.

The spelling of 21520858 in words is "twenty-one million, five hundred twenty thousand, eight hundred fifty-eight".