21126686 has 16 divisors (see below), whose sum is σ = 37386240. Its totient is φ = 8762040.

The previous prime is 21126683. The next prime is 21126691. The reversal of 21126686 is 68662112.

It is a super-2 number, since 2×21126686² = 892673722685192, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21126683) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23906 + ... + 24773.

It is an arithmetic number, because the mean of its divisors is an integer number (2336640).

Almost surely, 2^21126686 is an apocalyptic number.

21126686 is a deficient number, since it is larger than the sum of its proper divisors (16259554).

21126686 is a wasteful number, since it uses less digits than its factorization.

21126686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48719.

The product of its digits is 6912, while the sum is 32.

The square root of 21126686 is about 4596.3774866736. The cubic root of 21126686 is about 276.4460947402.

Adding to 21126686 its reverse (68662112), we get a palindrome (89788798).

It can be divided in two parts, 21126 and 686, that added together give a palindrome (21812).

The spelling of 21126686 in words is "twenty-one million, one hundred twenty-six thousand, six hundred eighty-six".