21040897 has 4 divisors (see below), whose sum is σ = 21052116. Its totient is φ = 21029680.

The previous prime is 21040891. The next prime is 21040919. The reversal of 21040897 is 79804012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10601536 + 10439361 = 3256^2 + 3231^2 .

It is a cyclic number.

It is not a de Polignac number, because 21040897 - 2¹⁹ = 20516609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040891) 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, 2038 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (5263029).

Almost surely, 2^21040897 is an apocalyptic number.

It is an amenable number.

21040897 is a deficient number, since it is larger than the sum of its proper divisors (11219).

21040897 is an equidigital number, since it uses as much as digits as its factorization.

21040897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11218.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21040897 is about 4587.0357530763. The cubic root of 21040897 is about 276.0713994722.

The spelling of 21040897 in words is "twenty-one million, forty thousand, eight hundred ninety-seven".