21457210 has 8 divisors (see below), whose sum is σ = 38622996. Its totient is φ = 8582880.

The previous prime is 21457207. The next prime is 21457253. The reversal of 21457210 is 1275412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17564481 + 3892729 = 4191^2 + 1973^2 .

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

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 3 ways as a sum of consecutive naturals, for example, 1072851 + ... + 1072870.

Almost surely, 2^21457210 is an apocalyptic number.

21457210 is a deficient number, since it is larger than the sum of its proper divisors (17165786).

21457210 is a wasteful number, since it uses less digits than its factorization.

21457210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2145728.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21457210 is about 4632.1927852800. The cubic root of 21457210 is about 277.8802945457.

The spelling of 21457210 in words is "twenty-one million, four hundred fifty-seven thousand, two hundred ten".