21210897 has 8 divisors (see below), whose sum is σ = 29769760. Its totient is φ = 13396320.

The previous prime is 21210881. The next prime is 21210901. The reversal of 21210897 is 79801212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21210897 - 2⁴ = 21210881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210877) 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, 186004 + ... + 186117.

It is an arithmetic number, because the mean of its divisors is an integer number (3721220).

Almost surely, 2^21210897 is an apocalyptic number.

It is an amenable number.

21210897 is a deficient number, since it is larger than the sum of its proper divisors (8558863).

21210897 is a wasteful number, since it uses less digits than its factorization.

21210897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372143.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 21210897 is about 4605.5289598482. The cubic root of 21210897 is about 276.8129126326.

The spelling of 21210897 in words is "twenty-one million, two hundred ten thousand, eight hundred ninety-seven".