21681486 has 32 divisors (see below), whose sum is σ = 48518400. Its totient is φ = 7176600.

The previous prime is 21681481. The next prime is 21681487. The reversal of 21681486 is 68418612.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21681486.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21681481) 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 15 ways as a sum of consecutive naturals, for example, 6825 + ... + 9483.

It is an arithmetic number, because the mean of its divisors is an integer number (1516200).

Almost surely, 2^21681486 is an apocalyptic number.

21681486 is an abundant number, since it is smaller than the sum of its proper divisors (26836914).

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

21681486 is a wasteful number, since it uses less digits than its factorization.

21681486 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2821 (or 2815 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 21681486 is about 4656.3382609085. The cubic root of 21681486 is about 278.8450984285.

The spelling of 21681486 in words is "twenty-one million, six hundred eighty-one thousand, four hundred eighty-six".