21969208 has 8 divisors (see below), whose sum is σ = 41192280. Its totient is φ = 10984600.

The previous prime is 21969203. The next prime is 21969221. The reversal of 21969208 is 80296912.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21969208² = 965292200294528, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21969203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1373068 + ... + 1373083.

It is an arithmetic number, because the mean of its divisors is an integer number (5149035).

Almost surely, 2^21969208 is an apocalyptic number.

It is an amenable number.

21969208 is a deficient number, since it is larger than the sum of its proper divisors (19223072).

21969208 is a wasteful number, since it uses less digits than its factorization.

21969208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2746157 (or 2746153 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21969208 is about 4687.1321722350. The cubic root of 21969208 is about 280.0731441563.

The spelling of 21969208 in words is "twenty-one million, nine hundred sixty-nine thousand, two hundred eight".