21297620 has 24 divisors (see below), whose sum is σ = 46169088. Its totient is φ = 8244000.

The previous prime is 21297569. The next prime is 21297631. The reversal of 21297620 is 2679212.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

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, 16556 + ... + 17795.

It is an arithmetic number, because the mean of its divisors is an integer number (1923712).

Almost surely, 2^21297620 is an apocalyptic number.

21297620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21297620 is an abundant number, since it is smaller than the sum of its proper divisors (24871468).

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

21297620 is a wasteful number, since it uses less digits than its factorization.

21297620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34391 (or 34389 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 21297620 is about 4614.9344524056. The cubic root of 21297620 is about 277.1896592839.

The spelling of 21297620 in words is "twenty-one million, two hundred ninety-seven thousand, six hundred twenty".