21997148 has 6 divisors (see below), whose sum is σ = 38495016. Its totient is φ = 10998572.

The previous prime is 21997139. The next prime is 21997159. The reversal of 21997148 is 84179912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2749640 + ... + 2749647.

It is an arithmetic number, because the mean of its divisors is an integer number (6415836).

Almost surely, 2^21997148 is an apocalyptic number.

It is an amenable number.

21997148 is a deficient number, since it is larger than the sum of its proper divisors (16497868).

21997148 is a wasteful number, since it uses less digits than its factorization.

21997148 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5499291 (or 5499289 counting only the distinct ones).

The product of its digits is 36288, while the sum is 41.

The square root of 21997148 is about 4690.1117257481. Note that the first 3 decimals coincide. The cubic root of 21997148 is about 280.1918243360.

The spelling of 21997148 in words is "twenty-one million, nine hundred ninety-seven thousand, one hundred forty-eight".