21658634 has 16 divisors (see below), whose sum is σ = 33516288. Its totient is φ = 10491312.

The previous prime is 21658607. The next prime is 21658639. The reversal of 21658634 is 43685612.

It is a junction number, because it is equal to n+sod(n) for n = 21658594 and 21658603.

It is not an unprimeable number, because it can be changed into a prime (21658639) 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 7 ways as a sum of consecutive naturals, for example, 8564 + ... + 10800.

It is an arithmetic number, because the mean of its divisors is an integer number (2094768).

Almost surely, 2^21658634 is an apocalyptic number.

21658634 is a deficient number, since it is larger than the sum of its proper divisors (11857654).

21658634 is a wasteful number, since it uses less digits than its factorization.

21658634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2389.

The product of its digits is 34560, while the sum is 35.

The square root of 21658634 is about 4653.8837544571. The cubic root of 21658634 is about 278.7470976391.

The spelling of 21658634 in words is "twenty-one million, six hundred fifty-eight thousand, six hundred thirty-four".