21797320 has 32 divisors (see below), whose sum is σ = 49228920. Its totient is φ = 8686080.

The previous prime is 21797297. The next prime is 21797327. The reversal of 21797320 is 2379712.

It can be written as a sum of positive squares in 4 ways, for example, as 2979076 + 18818244 = 1726^2 + 4338^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21797327) 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, 11650 + ... + 13390.

Almost surely, 2^21797320 is an apocalyptic number.

21797320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21797320 is an abundant number, since it is smaller than the sum of its proper divisors (27431600).

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

21797320 is a wasteful number, since it uses less digits than its factorization.

21797320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2065 (or 2061 counting only the distinct ones).

The product of its (nonzero) digits is 5292, while the sum is 31.

The square root of 21797320 is about 4668.7600066827. The cubic root of 21797320 is about 279.3407961936.

The spelling of 21797320 in words is "twenty-one million, seven hundred ninety-seven thousand, three hundred twenty".