21190686 has 48 divisors (see below), whose sum is σ = 47637504. Its totient is φ = 6232000.

The previous prime is 21190679. The next prime is 21190703. The reversal of 21190686 is 68609112.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 110851 + ... + 111041.

It is an arithmetic number, because the mean of its divisors is an integer number (992448).

Almost surely, 2^21190686 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21190686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23818752).

21190686 is an abundant number, since it is smaller than the sum of its proper divisors (26446818).

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

21190686 is a wasteful number, since it uses less digits than its factorization.

21190686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289 (or 248 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 21190686 is about 4603.3342264059. The cubic root of 21190686 is about 276.7249634415.

Adding to 21190686 its reverse (68609112), we get a palindrome (89799798).

The spelling of 21190686 in words is "twenty-one million, one hundred ninety thousand, six hundred eighty-six".