21698208 has 144 divisors (see below), whose sum is σ = 72334080. Its totient is φ = 6041088.

The previous prime is 21698207. The next prime is 21698213. The reversal of 21698208 is 80289612.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×21698208² = 941624460822528, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21698203) 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, 94638 + ... + 94866.

It is an arithmetic number, because the mean of its divisors is an integer number (502320).

Almost surely, 2^21698208 is an apocalyptic number.

21698208 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21698208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36167040).

21698208 is an abundant number, since it is smaller than the sum of its proper divisors (50635872).

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

21698208 is a wasteful number, since it uses less digits than its factorization.

21698208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299 (or 288 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 21698208 is about 4658.1335317915. The cubic root of 21698208 is about 278.9167670939.

The spelling of 21698208 in words is "twenty-one million, six hundred ninety-eight thousand, two hundred eight".