21957208 has 32 divisors (see below), whose sum is σ = 50672160. Its totient is φ = 8686080.

The previous prime is 21957193. The next prime is 21957209. The reversal of 21957208 is 80275912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21957209) 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, 14353 + ... + 15808.

It is an arithmetic number, because the mean of its divisors is an integer number (1583505).

Almost surely, 2^21957208 is an apocalyptic number.

21957208 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21957208 is an abundant number, since it is smaller than the sum of its proper divisors (28714952).

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

21957208 is a wasteful number, since it uses less digits than its factorization.

21957208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30187 (or 30183 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21957208 is about 4685.8518969340. The cubic root of 21957208 is about 280.0221411063.

The spelling of 21957208 in words is "twenty-one million, nine hundred fifty-seven thousand, two hundred eight".