21997792 has 12 divisors (see below), whose sum is σ = 43308216. Its totient is φ = 10998880.

The previous prime is 21997783. The next prime is 21997793. The reversal of 21997792 is 29779912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21997793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343684 + ... + 343747.

It is an arithmetic number, because the mean of its divisors is an integer number (3609018).

Almost surely, 2^21997792 is an apocalyptic number.

It is an amenable number.

21997792 is a deficient number, since it is larger than the sum of its proper divisors (21310424).

21997792 is an equidigital number, since it uses as much as digits as its factorization.

21997792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687441 (or 687433 counting only the distinct ones).

The product of its digits is 142884, while the sum is 46.

The square root of 21997792 is about 4690.1803803265. The cubic root of 21997792 is about 280.1945586567.

The spelling of 21997792 in words is "twenty-one million, nine hundred ninety-seven thousand, seven hundred ninety-two".