21997108 has 24 divisors (see below), whose sum is σ = 45908352. Its totient is φ = 9017184.

The previous prime is 21997103. The next prime is 21997139. The reversal of 21997108 is 80179912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21997103) 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 in 7 ways as a sum of consecutive naturals, for example, 16435 + ... + 17722.

It is an arithmetic number, because the mean of its divisors is an integer number (1912848).

Almost surely, 2^21997108 is an apocalyptic number.

21997108 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21997108 is an abundant number, since it is smaller than the sum of its proper divisors (23911244).

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

21997108 is a wasteful number, since it uses less digits than its factorization.

21997108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34191 (or 34189 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21997108 is about 4690.1074614554. The cubic root of 21997108 is about 280.1916545006.

The spelling of 21997108 in words is "twenty-one million, nine hundred ninety-seven thousand, one hundred eight".