21698872 has 32 divisors (see below), whose sum is σ = 45007200. Its totient is φ = 9742464.

The previous prime is 21698861. The next prime is 21698879. The reversal of 21698872 is 27889612.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21698879) 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, 1029 + ... + 6667.

It is an arithmetic number, because the mean of its divisors is an integer number (1406475).

Almost surely, 2^21698872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21698872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22503600).

21698872 is an abundant number, since it is smaller than the sum of its proper divisors (23308328).

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

21698872 is a wasteful number, since it uses less digits than its factorization.

21698872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5695 (or 5691 counting only the distinct ones).

The product of its digits is 96768, while the sum is 43.

The square root of 21698872 is about 4658.2048044284. The cubic root of 21698872 is about 278.9196121652.

The spelling of 21698872 in words is "twenty-one million, six hundred ninety-eight thousand, eight hundred seventy-two".