21897361 has 4 divisors (see below), whose sum is σ = 21906724. Its totient is φ = 21888000.

The previous prime is 21897313. The next prime is 21897371. The reversal of 21897361 is 16379812.

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 9960336 + 11937025 = 3156^2 + 3455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21897361 - 2¹⁷ = 21766289 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21897361.

It is not an unprimeable number, because it can be changed into a prime (21897371) 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, 2161 + ... + 6961.

It is an arithmetic number, because the mean of its divisors is an integer number (5476681).

Almost surely, 2^21897361 is an apocalyptic number.

It is an amenable number.

21897361 is a deficient number, since it is larger than the sum of its proper divisors (9363).

21897361 is an equidigital number, since it uses as much as digits as its factorization.

21897361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9362.

The product of its digits is 18144, while the sum is 37.

The square root of 21897361 is about 4679.4616143313. The cubic root of 21897361 is about 279.7674983191.

It can be divided in two parts, 218 and 97361, that added together give a palindrome (97579).

The spelling of 21897361 in words is "twenty-one million, eight hundred ninety-seven thousand, three hundred sixty-one".