21689694 has 48 divisors (see below), whose sum is σ = 52498992. Its totient is φ = 6671808.

The previous prime is 21689693. The next prime is 21689741. The reversal of 21689694 is 49698612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21689693) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4602 + ... + 8034.

It is an arithmetic number, because the mean of its divisors is an integer number (1093729).

Almost surely, 2^21689694 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21689694, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26249496).

21689694 is an abundant number, since it is smaller than the sum of its proper divisors (30809298).

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

21689694 is a wasteful number, since it uses less digits than its factorization.

21689694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3463 (or 3451 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 21689694 is about 4657.2195567742. The cubic root of 21689694 is about 278.8802816229.

The spelling of 21689694 in words is "twenty-one million, six hundred eighty-nine thousand, six hundred ninety-four".