21285697 has 4 divisors (see below), whose sum is σ = 21474180. Its totient is φ = 21097216.

The previous prime is 21285679. The next prime is 21285703. The reversal of 21285697 is 79658212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7750656 + 13535041 = 2784^2 + 3679^2 .

It is a cyclic number.

It is not a de Polignac number, because 21285697 - 2⁷ = 21285569 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21285647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94072 + ... + 94297.

It is an arithmetic number, because the mean of its divisors is an integer number (5368545).

Almost surely, 2^21285697 is an apocalyptic number.

It is an amenable number.

21285697 is a deficient number, since it is larger than the sum of its proper divisors (188483).

21285697 is a wasteful number, since it uses less digits than its factorization.

21285697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188482.

The product of its digits is 60480, while the sum is 40.

The square root of 21285697 is about 4613.6424872328. The cubic root of 21285697 is about 277.1379234681.

The spelling of 21285697 in words is "twenty-one million, two hundred eighty-five thousand, six hundred ninety-seven".